| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
bonding: fix xfrm real_dev null pointer dereference
We shouldn't set real_dev to NULL because packets can be in transit and
xfrm might call xdo_dev_offload_ok() in parallel. All callbacks assume
real_dev is set.
Example trace:
kernel: BUG: unable to handle page fault for address: 0000000000001030
kernel: bond0: (slave eni0np1): making interface the new active one
kernel: #PF: supervisor write access in kernel mode
kernel: #PF: error_code(0x0002) - not-present page
kernel: PGD 0 P4D 0
kernel: Oops: 0002 [#1] PREEMPT SMP
kernel: CPU: 4 PID: 2237 Comm: ping Not tainted 6.7.7+ #12
kernel: Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014
kernel: RIP: 0010:nsim_ipsec_offload_ok+0xc/0x20 [netdevsim]
kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
kernel: Code: e0 0f 0b 48 83 7f 38 00 74 de 0f 0b 48 8b 47 08 48 8b 37 48 8b 78 40 e9 b2 e5 9a d7 66 90 0f 1f 44 00 00 48 8b 86 80 02 00 00 <83> 80 30 10 00 00 01 b8 01 00 00 00 c3 0f 1f 80 00 00 00 00 0f 1f
kernel: bond0: (slave eni0np1): making interface the new active one
kernel: RSP: 0018:ffffabde81553b98 EFLAGS: 00010246
kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
kernel:
kernel: RAX: 0000000000000000 RBX: ffff9eb404e74900 RCX: ffff9eb403d97c60
kernel: RDX: ffffffffc090de10 RSI: ffff9eb404e74900 RDI: ffff9eb3c5de9e00
kernel: RBP: ffff9eb3c0a42000 R08: 0000000000000010 R09: 0000000000000014
kernel: R10: 7974203030303030 R11: 3030303030303030 R12: 0000000000000000
kernel: R13: ffff9eb3c5de9e00 R14: ffffabde81553cc8 R15: ffff9eb404c53000
kernel: FS: 00007f2a77a3ad00(0000) GS:ffff9eb43bd00000(0000) knlGS:0000000000000000
kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
kernel: CR2: 0000000000001030 CR3: 00000001122ab000 CR4: 0000000000350ef0
kernel: bond0: (slave eni0np1): making interface the new active one
kernel: Call Trace:
kernel: <TASK>
kernel: ? __die+0x1f/0x60
kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
kernel: ? page_fault_oops+0x142/0x4c0
kernel: ? do_user_addr_fault+0x65/0x670
kernel: ? kvm_read_and_reset_apf_flags+0x3b/0x50
kernel: bond0: (slave eni0np1): making interface the new active one
kernel: ? exc_page_fault+0x7b/0x180
kernel: ? asm_exc_page_fault+0x22/0x30
kernel: ? nsim_bpf_uninit+0x50/0x50 [netdevsim]
kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
kernel: ? nsim_ipsec_offload_ok+0xc/0x20 [netdevsim]
kernel: bond0: (slave eni0np1): making interface the new active one
kernel: bond_ipsec_offload_ok+0x7b/0x90 [bonding]
kernel: xfrm_output+0x61/0x3b0
kernel: bond0: (slave eni0np1): bond_ipsec_add_sa_all: failed to add SA
kernel: ip_push_pending_frames+0x56/0x80 |
| In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: core: Check for unset descriptor
Make sure the descriptor has been set before looking at maxpacket.
This fixes a null pointer panic in this case.
This may happen if the gadget doesn't properly set up the endpoint
for the current speed, or the gadget descriptors are malformed and
the descriptor for the speed/endpoint are not found.
No current gadget driver is known to have this problem, but this
may cause a hard-to-find bug during development of new gadgets. |
| In the Linux kernel, the following vulnerability has been resolved:
jfs: fix null ptr deref in dtInsertEntry
[syzbot reported]
general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 PID: 5061 Comm: syz-executor404 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
RIP: 0010:dtInsertEntry+0xd0c/0x1780 fs/jfs/jfs_dtree.c:3713
...
[Analyze]
In dtInsertEntry(), when the pointer h has the same value as p, after writing
name in UniStrncpy_to_le(), p->header.flag will be cleared. This will cause the
previously true judgment "p->header.flag & BT-LEAF" to change to no after writing
the name operation, this leads to entering an incorrect branch and accessing the
uninitialized object ih when judging this condition for the second time.
[Fix]
After got the page, check freelist first, if freelist == 0 then exit dtInsert()
and return -EINVAL. |
| In the Linux kernel, the following vulnerability has been resolved:
sctp: Fix null-ptr-deref in reuseport_add_sock().
syzbot reported a null-ptr-deref while accessing sk2->sk_reuseport_cb in
reuseport_add_sock(). [0]
The repro first creates a listener with SO_REUSEPORT. Then, it creates
another listener on the same port and concurrently closes the first
listener.
The second listen() calls reuseport_add_sock() with the first listener as
sk2, where sk2->sk_reuseport_cb is not expected to be cleared concurrently,
but the close() does clear it by reuseport_detach_sock().
The problem is SCTP does not properly synchronise reuseport_alloc(),
reuseport_add_sock(), and reuseport_detach_sock().
The caller of reuseport_alloc() and reuseport_{add,detach}_sock() must
provide synchronisation for sockets that are classified into the same
reuseport group.
Otherwise, such sockets form multiple identical reuseport groups, and
all groups except one would be silently dead.
1. Two sockets call listen() concurrently
2. No socket in the same group found in sctp_ep_hashtable[]
3. Two sockets call reuseport_alloc() and form two reuseport groups
4. Only one group hit first in __sctp_rcv_lookup_endpoint() receives
incoming packets
Also, the reported null-ptr-deref could occur.
TCP/UDP guarantees that would not happen by holding the hash bucket lock.
Let's apply the locking strategy to __sctp_hash_endpoint() and
__sctp_unhash_endpoint().
[0]:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 UID: 0 PID: 10230 Comm: syz-executor119 Not tainted 6.10.0-syzkaller-12585-g301927d2d2eb #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:reuseport_add_sock+0x27e/0x5e0 net/core/sock_reuseport.c:350
Code: 00 0f b7 5d 00 bf 01 00 00 00 89 de e8 1b a4 ff f7 83 fb 01 0f 85 a3 01 00 00 e8 6d a0 ff f7 49 8d 7e 12 48 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 4b 02 00 00 41 0f b7 5e 12 49 8d 7e 14
RSP: 0018:ffffc9000b947c98 EFLAGS: 00010202
RAX: 0000000000000002 RBX: ffff8880252ddf98 RCX: ffff888079478000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000012
RBP: 0000000000000001 R08: ffffffff8993e18d R09: 1ffffffff1fef385
R10: dffffc0000000000 R11: fffffbfff1fef386 R12: ffff8880252ddac0
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 00007f24e45b96c0(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffcced5f7b8 CR3: 00000000241be000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__sctp_hash_endpoint net/sctp/input.c:762 [inline]
sctp_hash_endpoint+0x52a/0x600 net/sctp/input.c:790
sctp_listen_start net/sctp/socket.c:8570 [inline]
sctp_inet_listen+0x767/0xa20 net/sctp/socket.c:8625
__sys_listen_socket net/socket.c:1883 [inline]
__sys_listen+0x1b7/0x230 net/socket.c:1894
__do_sys_listen net/socket.c:1902 [inline]
__se_sys_listen net/socket.c:1900 [inline]
__x64_sys_listen+0x5a/0x70 net/socket.c:1900
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f24e46039b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 1a 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f24e45b9228 EFLAGS: 00000246 ORIG_RAX: 0000000000000032
RAX: ffffffffffffffda RBX: 00007f24e468e428 RCX: 00007f24e46039b9
RDX: 00007f24e46039b9 RSI: 0000000000000003 RDI: 0000000000000004
RBP: 00007f24e468e420 R08: 00007f24e45b96c0 R09: 00007f24e45b96c0
R10: 00007f24e45b96c0 R11: 0000000000000246 R12: 00007f24e468e42c
R13:
---truncated--- |
| libxml2 before 2.12.10 and 2.13.x before 2.13.6 has a NULL pointer dereference in xmlPatMatch in pattern.c. |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: fix NULL dereference at band check in starting tx ba session
In MLD connection, link_data/link_conf are dynamically allocated. They
don't point to vif->bss_conf. So, there will be no chanreq assigned to
vif->bss_conf and then the chan will be NULL. Tweak the code to check
ht_supported/vht_supported/has_he/has_eht on sta deflink.
Crash log (with rtw89 version under MLO development):
[ 9890.526087] BUG: kernel NULL pointer dereference, address: 0000000000000000
[ 9890.526102] #PF: supervisor read access in kernel mode
[ 9890.526105] #PF: error_code(0x0000) - not-present page
[ 9890.526109] PGD 0 P4D 0
[ 9890.526114] Oops: 0000 [#1] PREEMPT SMP PTI
[ 9890.526119] CPU: 2 PID: 6367 Comm: kworker/u16:2 Kdump: loaded Tainted: G OE 6.9.0 #1
[ 9890.526123] Hardware name: LENOVO 2356AD1/2356AD1, BIOS G7ETB3WW (2.73 ) 11/28/2018
[ 9890.526126] Workqueue: phy2 rtw89_core_ba_work [rtw89_core]
[ 9890.526203] RIP: 0010:ieee80211_start_tx_ba_session (net/mac80211/agg-tx.c:618 (discriminator 1)) mac80211
[ 9890.526279] Code: f7 e8 d5 93 3e ea 48 83 c4 28 89 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 49 8b 84 24 e0 f1 ff ff 48 8b 80 90 1b 00 00 <83> 38 03 0f 84 37 fe ff ff bb ea ff ff ff eb cc 49 8b 84 24 10 f3
All code
========
0: f7 e8 imul %eax
2: d5 (bad)
3: 93 xchg %eax,%ebx
4: 3e ea ds (bad)
6: 48 83 c4 28 add $0x28,%rsp
a: 89 d8 mov %ebx,%eax
c: 5b pop %rbx
d: 41 5c pop %r12
f: 41 5d pop %r13
11: 41 5e pop %r14
13: 41 5f pop %r15
15: 5d pop %rbp
16: c3 retq
17: cc int3
18: cc int3
19: cc int3
1a: cc int3
1b: 49 8b 84 24 e0 f1 ff mov -0xe20(%r12),%rax
22: ff
23: 48 8b 80 90 1b 00 00 mov 0x1b90(%rax),%rax
2a:* 83 38 03 cmpl $0x3,(%rax) <-- trapping instruction
2d: 0f 84 37 fe ff ff je 0xfffffffffffffe6a
33: bb ea ff ff ff mov $0xffffffea,%ebx
38: eb cc jmp 0x6
3a: 49 rex.WB
3b: 8b .byte 0x8b
3c: 84 24 10 test %ah,(%rax,%rdx,1)
3f: f3 repz
Code starting with the faulting instruction
===========================================
0: 83 38 03 cmpl $0x3,(%rax)
3: 0f 84 37 fe ff ff je 0xfffffffffffffe40
9: bb ea ff ff ff mov $0xffffffea,%ebx
e: eb cc jmp 0xffffffffffffffdc
10: 49 rex.WB
11: 8b .byte 0x8b
12: 84 24 10 test %ah,(%rax,%rdx,1)
15: f3 repz
[ 9890.526285] RSP: 0018:ffffb8db09013d68 EFLAGS: 00010246
[ 9890.526291] RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff9308e0d656c8
[ 9890.526295] RDX: 0000000000000000 RSI: ffffffffab99460b RDI: ffffffffab9a7685
[ 9890.526300] RBP: ffffb8db09013db8 R08: 0000000000000000 R09: 0000000000000873
[ 9890.526304] R10: ffff9308e0d64800 R11: 0000000000000002 R12: ffff9308e5ff6e70
[ 9890.526308] R13: ffff930952500e20 R14: ffff9309192a8c00 R15: 0000000000000000
[ 9890.526313] FS: 0000000000000000(0000) GS:ffff930b4e700000(0000) knlGS:0000000000000000
[ 9890.526316] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 9890.526318] CR2: 0000000000000000 CR3: 0000000391c58005 CR4: 00000000001706f0
[ 9890.526321] Call Trace:
[ 9890.526324] <TASK>
[ 9890.526327] ? show_regs (arch/x86/kernel/dumpstack.c:479)
[ 9890.526335] ? __die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434)
[ 9890.526340] ? page_fault_oops (arch/x86/mm/fault.c:713)
[ 9890.526347] ? search_module_extables (kernel/module/main.c:3256 (discriminator
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu/pm: Fix the null pointer dereference for smu7
optimize the code to avoid pass a null pointer (hwmgr->backend)
to function smu7_update_edc_leakage_table. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu: Fix the null pointer dereference to ras_manager
Check ras_manager before using it |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdgpu/pm: Fix the null pointer dereference in apply_state_adjust_rules
Check the pointer value to fix potential null pointer
dereference |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amd/pm: Fix the null pointer dereference for vega10_hwmgr
Check return value and conduct null pointer handling to avoid null pointer dereference. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Add null checks for 'stream' and 'plane' before dereferencing
This commit adds null checks for the 'stream' and 'plane' variables in
the dcn30_apply_idle_power_optimizations function. These variables were
previously assumed to be null at line 922, but they were used later in
the code without checking if they were null. This could potentially lead
to a null pointer dereference, which would cause a crash.
The null checks ensure that 'stream' and 'plane' are not null before
they are used, preventing potential crashes.
Fixes the below static smatch checker:
drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn30/dcn30_hwseq.c:938 dcn30_apply_idle_power_optimizations() error: we previously assumed 'stream' could be null (see line 922)
drivers/gpu/drm/amd/amdgpu/../display/dc/hwss/dcn30/dcn30_hwseq.c:940 dcn30_apply_idle_power_optimizations() error: we previously assumed 'plane' could be null (see line 922) |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Add null checker before passing variables
Checks null pointer before passing variables to functions.
This fixes 3 NULL_RETURNS issues reported by Coverity. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: Skip Recompute DSC Params if no Stream on Link
[why]
Encounter NULL pointer dereference uner mst + dsc setup.
BUG: kernel NULL pointer dereference, address: 0000000000000008
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 4 PID: 917 Comm: sway Not tainted 6.3.9-arch1-1 #1 124dc55df4f5272ccb409f39ef4872fc2b3376a2
Hardware name: LENOVO 20NKS01Y00/20NKS01Y00, BIOS R12ET61W(1.31 ) 07/28/2022
RIP: 0010:drm_dp_atomic_find_time_slots+0x5e/0x260 [drm_display_helper]
Code: 01 00 00 48 8b 85 60 05 00 00 48 63 80 88 00 00 00 3b 43 28 0f 8d 2e 01 00 00 48 8b 53 30 48 8d 04 80 48 8d 04 c2 48 8b 40 18 <48> 8>
RSP: 0018:ffff960cc2df77d8 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff8afb87e81280 RCX: 0000000000000224
RDX: ffff8afb9ee37c00 RSI: ffff8afb8da1a578 RDI: ffff8afb87e81280
RBP: ffff8afb83d67000 R08: 0000000000000001 R09: ffff8afb9652f850
R10: ffff960cc2df7908 R11: 0000000000000002 R12: 0000000000000000
R13: ffff8afb8d7688a0 R14: ffff8afb8da1a578 R15: 0000000000000224
FS: 00007f4dac35ce00(0000) GS:ffff8afe30b00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 000000010ddc6000 CR4: 00000000003506e0
Call Trace:
<TASK>
? __die+0x23/0x70
? page_fault_oops+0x171/0x4e0
? plist_add+0xbe/0x100
? exc_page_fault+0x7c/0x180
? asm_exc_page_fault+0x26/0x30
? drm_dp_atomic_find_time_slots+0x5e/0x260 [drm_display_helper 0e67723696438d8e02b741593dd50d80b44c2026]
? drm_dp_atomic_find_time_slots+0x28/0x260 [drm_display_helper 0e67723696438d8e02b741593dd50d80b44c2026]
compute_mst_dsc_configs_for_link+0x2ff/0xa40 [amdgpu 62e600d2a75e9158e1cd0a243bdc8e6da040c054]
? fill_plane_buffer_attributes+0x419/0x510 [amdgpu 62e600d2a75e9158e1cd0a243bdc8e6da040c054]
compute_mst_dsc_configs_for_state+0x1e1/0x250 [amdgpu 62e600d2a75e9158e1cd0a243bdc8e6da040c054]
amdgpu_dm_atomic_check+0xecd/0x1190 [amdgpu 62e600d2a75e9158e1cd0a243bdc8e6da040c054]
drm_atomic_check_only+0x5c5/0xa40
drm_mode_atomic_ioctl+0x76e/0xbc0
[how]
dsc recompute should be skipped if no mode change detected on the new
request. If detected, keep checking whether the stream is already on
current state or not.
(cherry picked from commit 8151a6c13111b465dbabe07c19f572f7cbd16fef) |
| In the Linux kernel, the following vulnerability has been resolved:
drm/client: fix null pointer dereference in drm_client_modeset_probe
In drm_client_modeset_probe(), the return value of drm_mode_duplicate() is
assigned to modeset->mode, which will lead to a possible NULL pointer
dereference on failure of drm_mode_duplicate(). Add a check to avoid npd. |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: MGMT: Add error handling to pair_device()
hci_conn_params_add() never checks for a NULL value and could lead to a NULL
pointer dereference causing a crash.
Fixed by adding error handling in the function. |
| In the Linux kernel, the following vulnerability has been resolved:
PCI: endpoint: Clean up error handling in vpci_scan_bus()
Smatch complains about inconsistent NULL checking in vpci_scan_bus():
drivers/pci/endpoint/functions/pci-epf-vntb.c:1024 vpci_scan_bus() error: we previously assumed 'vpci_bus' could be null (see line 1021)
Instead of printing an error message and then crashing we should return
an error code and clean up.
Also the NULL check is reversed so it prints an error for success
instead of failure. |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5: Always drain health in shutdown callback
There is no point in recovery during device shutdown. if health
work started need to wait for it to avoid races and NULL pointer
access.
Hence, drain health WQ on shutdown callback. |
| In the Linux kernel, the following vulnerability has been resolved:
remoteproc: imx_rproc: Skip over memory region when node value is NULL
In imx_rproc_addr_init() "nph = of_count_phandle_with_args()" just counts
number of phandles. But phandles may be empty. So of_parse_phandle() in
the parsing loop (0 < a < nph) may return NULL which is later dereferenced.
Adjust this issue by adding NULL-return check.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
[Fixed title to fit within the prescribed 70-75 charcters] |
| In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix to truncate preallocated blocks in f2fs_file_open()
chenyuwen reports a f2fs bug as below:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000011
fscrypt_set_bio_crypt_ctx+0x78/0x1e8
f2fs_grab_read_bio+0x78/0x208
f2fs_submit_page_read+0x44/0x154
f2fs_get_read_data_page+0x288/0x5f4
f2fs_get_lock_data_page+0x60/0x190
truncate_partial_data_page+0x108/0x4fc
f2fs_do_truncate_blocks+0x344/0x5f0
f2fs_truncate_blocks+0x6c/0x134
f2fs_truncate+0xd8/0x200
f2fs_iget+0x20c/0x5ac
do_garbage_collect+0x5d0/0xf6c
f2fs_gc+0x22c/0x6a4
f2fs_disable_checkpoint+0xc8/0x310
f2fs_fill_super+0x14bc/0x1764
mount_bdev+0x1b4/0x21c
f2fs_mount+0x20/0x30
legacy_get_tree+0x50/0xbc
vfs_get_tree+0x5c/0x1b0
do_new_mount+0x298/0x4cc
path_mount+0x33c/0x5fc
__arm64_sys_mount+0xcc/0x15c
invoke_syscall+0x60/0x150
el0_svc_common+0xb8/0xf8
do_el0_svc+0x28/0xa0
el0_svc+0x24/0x84
el0t_64_sync_handler+0x88/0xec
It is because inode.i_crypt_info is not initialized during below path:
- mount
- f2fs_fill_super
- f2fs_disable_checkpoint
- f2fs_gc
- f2fs_iget
- f2fs_truncate
So, let's relocate truncation of preallocated blocks to f2fs_file_open(),
after fscrypt_file_open(). |
| In the Linux kernel, the following vulnerability has been resolved:
md: fix deadlock between mddev_suspend and flush bio
Deadlock occurs when mddev is being suspended while some flush bio is in
progress. It is a complex issue.
T1. the first flush is at the ending stage, it clears 'mddev->flush_bio'
and tries to submit data, but is blocked because mddev is suspended
by T4.
T2. the second flush sets 'mddev->flush_bio', and attempts to queue
md_submit_flush_data(), which is already running (T1) and won't
execute again if on the same CPU as T1.
T3. the third flush inc active_io and tries to flush, but is blocked because
'mddev->flush_bio' is not NULL (set by T2).
T4. mddev_suspend() is called and waits for active_io dec to 0 which is inc
by T3.
T1 T2 T3 T4
(flush 1) (flush 2) (third 3) (suspend)
md_submit_flush_data
mddev->flush_bio = NULL;
.
. md_flush_request
. mddev->flush_bio = bio
. queue submit_flushes
. .
. . md_handle_request
. . active_io + 1
. . md_flush_request
. . wait !mddev->flush_bio
. .
. . mddev_suspend
. . wait !active_io
. .
. submit_flushes
. queue_work md_submit_flush_data
. //md_submit_flush_data is already running (T1)
.
md_handle_request
wait resume
The root issue is non-atomic inc/dec of active_io during flush process.
active_io is dec before md_submit_flush_data is queued, and inc soon
after md_submit_flush_data() run.
md_flush_request
active_io + 1
submit_flushes
active_io - 1
md_submit_flush_data
md_handle_request
active_io + 1
make_request
active_io - 1
If active_io is dec after md_handle_request() instead of within
submit_flushes(), make_request() can be called directly intead of
md_handle_request() in md_submit_flush_data(), and active_io will
only inc and dec once in the whole flush process. Deadlock will be
fixed.
Additionally, the only difference between fixing the issue and before is
that there is no return error handling of make_request(). But after
previous patch cleaned md_write_start(), make_requst() only return error
in raid5_make_request() by dm-raid, see commit 41425f96d7aa ("dm-raid456,
md/raid456: fix a deadlock for dm-raid456 while io concurrent with
reshape)". Since dm always splits data and flush operation into two
separate io, io size of flush submitted by dm always is 0, make_request()
will not be called in md_submit_flush_data(). To prevent future
modifications from introducing issues, add WARN_ON to ensure
make_request() no error is returned in this context. |
