* use-after-free" with v5.10.y caused by backport of a298232ee6b9 ("io_uring: fix link timeout refs")
@ 2021-07-26 10:29 Sudip Mukherjee
2021-07-26 10:57 ` Pavel Begunkov
0 siblings, 1 reply; 5+ messages in thread
From: Sudip Mukherjee @ 2021-07-26 10:29 UTC (permalink / raw)
To: Pavel Begunkov; +Cc: stable, Greg Kroah-Hartman, Jens Axboe, Sasha Levin
Hi Pavel,
We had been running syzkaller on v5.10.y and a "use after free" is being
reported for v5.10.43+ kernels.
The syzkaller report is at: https://elisa-builder-00.iol.unh.edu/syzkaller/file?name=crashes%2fb23bc4ad436bbe4afc620d9503730ddd78c382c0%2freport19
The trace is:
refcount_t: underflow; use-after-free.
WARNING: CPU: 1 PID: 8769 at lib/refcount.c:28 refcount_warn_saturate+0x103/0x1f0 lib/refcount.c:28
Modules linked in:
CPU: 1 PID: 8769 Comm: syz-executor.6 Not tainted 5.10.52 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
RIP: 0010:refcount_warn_saturate+0x103/0x1f0 lib/refcount.c:28
Code: 1d d2 63 54 03 31 ff 89 de e8 c9 22 51 ff 84 db 75 a3 e8 90 29 51 ff 48 c7 c7 20 38 3b 84 c6 05 b2 63 54 03 01 e8 cc 0c c9 01 <0f> 0b eb 87 e8 74 29 51 ff 0f b6 1d 9b 63 54 03 31 ff 89 de e8 94
RSP: 0018:ffff88804ec5f9f8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000040000 RSI: ffffffff81293053 RDI: ffffed1009d8bf31
RBP: ffff888048ceb41c R08: 0000000000000001 R09: ffff88806cf1ff9b
R10: 0000000000000000 R11: 0000000000000001 R12: ffff888048ceb41c
R13: 0000000000000000 R14: ffff888048ceb558 R15: ffff88800c857180
FS: 00007f0e798e9700(0000) GS:ffff88806cf00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558bbbc7d898 CR3: 0000000048fb6000 CR4: 0000000000350ee0
Call Trace:
__refcount_sub_and_test include/linux/refcount.h:283 [inline]
__refcount_dec_and_test include/linux/refcount.h:315 [inline]
refcount_dec_and_test include/linux/refcount.h:333 [inline]
io_put_req+0xc6/0x100 fs/io_uring.c:2220
__io_queue_sqe+0x2b1/0xd00 fs/io_uring.c:6358
io_queue_sqe+0x5bc/0x1020 fs/io_uring.c:6403
io_queue_link_head fs/io_uring.c:6414 [inline]
io_submit_sqe fs/io_uring.c:6455 [inline]
io_submit_sqes+0x17b5/0x2310 fs/io_uring.c:6700
__do_sys_io_uring_enter+0x1092/0x1910 fs/io_uring.c:9092
do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x466609
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0e798e9188 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 0000000000466609
RDX: 0000000000000000 RSI: 00000000000058ab RDI: 0000000000000004
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80
R13: 00007ffdbe4f1c5f R14: 00007f0e798e9300 R15: 0000000000022000
irq event stamp: 1473
hardirqs last enabled at (1483): [<ffffffff8128f5d9>] console_unlock+0x929/0xb30 kernel/printk/printk.c:2552
hardirqs last disabled at (1494): [<ffffffff83c43a7b>] sysvec_apic_timer_interrupt+0xb/0xa0 arch/x86/kernel/apic/apic.c:1095
softirqs last enabled at (1072): [<ffffffff83e00f92>] asm_call_irq_on_stack+0x12/0x20
softirqs last disabled at (1067): [<ffffffff83e00f92>] asm_call_irq_on_stack+0x12/0x20
I have done a bisect and the commit causing this is: 0b2a990e5d2f ("io_uring: fix link timeout refs")
The git bisect log is:
# bad: [71046eac2db9aeccf10763d034a1a123911c9a81] Linux 5.10.53
# good: [2c85ebc57b3e1817b6ce1a6b703928e113a90442] Linux 5.10
git bisect start 'v5.10.53' 'v5.10'
# good: [d29c38dd926d5aba65d177c0b99381ea632ff0a0] staging: rtl8192e: Change state information from u16 to u8
git bisect good d29c38dd926d5aba65d177c0b99381ea632ff0a0
# good: [b67c3d74adc3f7f832f57c170234bbe1fc69c87c] Revert "net: fujitsu: fix a potential NULL pointer dereference"
git bisect good b67c3d74adc3f7f832f57c170234bbe1fc69c87c
# bad: [f1f30b3373df2e5ab96dd3781df5c02e5366f845] mmc: usdhi6rol0: fix error return code in usdhi6_probe()
git bisect bad f1f30b3373df2e5ab96dd3781df5c02e5366f845
# bad: [3d60457d74d9cc7b36f78f9cb74f29bc6182c1e8] cxgb4: fix endianness when flashing boot image
git bisect bad 3d60457d74d9cc7b36f78f9cb74f29bc6182c1e8
# bad: [3a6b69221f96f87c680bbc9fba01db3415b18f27] drm/amdgpu: make sure we unpin the UVD BO
git bisect bad 3a6b69221f96f87c680bbc9fba01db3415b18f27
# good: [65859eca4dff1af0db5e36d1cfbac15b834c6a65] Linux 5.10.42
git bisect good 65859eca4dff1af0db5e36d1cfbac15b834c6a65
# good: [a1bf16616d8351a2e79400d6d19608befb2ce1dd] ixgbe: add correct exception tracing for XDP
git bisect good a1bf16616d8351a2e79400d6d19608befb2ce1dd
# bad: [c5155c741a484e036e7997420559431a951f2106] wireguard: allowedips: allocate nodes in kmem_cache
git bisect bad c5155c741a484e036e7997420559431a951f2106
# good: [3c23e23c7ad9844a645f4e2bd8ec34a0a2ee5514] riscv: vdso: fix and clean-up Makefile
git bisect good 3c23e23c7ad9844a645f4e2bd8ec34a0a2ee5514
# bad: [74caf718cc7422a957aac381c73d798c0a999a65] Bluetooth: use correct lock to prevent UAF of hdev object
git bisect bad 74caf718cc7422a957aac381c73d798c0a999a65
# bad: [58f4d45d8d4d391f60b6f0db6308df1994a265b3] drm/amdgpu/vcn3: add cancel_delayed_work_sync before power gate
git bisect bad 58f4d45d8d4d391f60b6f0db6308df1994a265b3
# bad: [ec72cb50c1db39816eae7296686449bba8ca0b2e] io_uring: use better types for cflags
git bisect bad ec72cb50c1db39816eae7296686449bba8ca0b2e
# bad: [0b2a990e5d2f76d020cb840c456e6ec5f0c27530] io_uring: fix link timeout refs
git bisect bad 0b2a990e5d2f76d020cb840c456e6ec5f0c27530
# first bad commit: [0b2a990e5d2f76d020cb840c456e6ec5f0c27530] io_uring: fix link timeout refs
The mainline commit for the bad LTS commit is:
a298232ee6b9 ("io_uring: fix link timeout refs") and I have tested the
reproducer on mainline with 'a298232ee6b9' as HEAD and the issue is not
reproduced. I think we are missing some change in v5.10.y kernel which
was missed while the mainline fix was backported to LTS.
I can reproduce the crash using syzkaller and will be happy to test any
patch for this.
--
Regards
Sudip
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: use-after-free" with v5.10.y caused by backport of a298232ee6b9 ("io_uring: fix link timeout refs") 2021-07-26 10:29 use-after-free" with v5.10.y caused by backport of a298232ee6b9 ("io_uring: fix link timeout refs") Sudip Mukherjee @ 2021-07-26 10:57 ` Pavel Begunkov 2021-07-26 11:08 ` Greg Kroah-Hartman 0 siblings, 1 reply; 5+ messages in thread From: Pavel Begunkov @ 2021-07-26 10:57 UTC (permalink / raw) To: Sudip Mukherjee; +Cc: stable, Greg Kroah-Hartman, Jens Axboe, Sasha Levin On 7/26/21 11:29 AM, Sudip Mukherjee wrote: > Hi Pavel, > > We had been running syzkaller on v5.10.y and a "use after free" is being > reported for v5.10.43+ kernels. "... # 5.12+", weird, but perhaps due to dependencies. Thanks for letting know. Greg, Sasha, should be same as reported for 5.12 https://www.spinics.net/lists/stable/msg485116.html Can you try to apply it to 5.10 or should I resend? > The syzkaller report is at: https://elisa-builder-00.iol.unh.edu/syzkaller/file?name=crashes%2fb23bc4ad436bbe4afc620d9503730ddd78c382c0%2freport19 > > The trace is: > > refcount_t: underflow; use-after-free. > WARNING: CPU: 1 PID: 8769 at lib/refcount.c:28 refcount_warn_saturate+0x103/0x1f0 lib/refcount.c:28 > Modules linked in: > CPU: 1 PID: 8769 Comm: syz-executor.6 Not tainted 5.10.52 #1 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014 > RIP: 0010:refcount_warn_saturate+0x103/0x1f0 lib/refcount.c:28 > Code: 1d d2 63 54 03 31 ff 89 de e8 c9 22 51 ff 84 db 75 a3 e8 90 29 51 ff 48 c7 c7 20 38 3b 84 c6 05 b2 63 54 03 01 e8 cc 0c c9 01 <0f> 0b eb 87 e8 74 29 51 ff 0f b6 1d 9b 63 54 03 31 ff 89 de e8 94 > RSP: 0018:ffff88804ec5f9f8 EFLAGS: 00010286 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: 0000000000040000 RSI: ffffffff81293053 RDI: ffffed1009d8bf31 > RBP: ffff888048ceb41c R08: 0000000000000001 R09: ffff88806cf1ff9b > R10: 0000000000000000 R11: 0000000000000001 R12: ffff888048ceb41c > R13: 0000000000000000 R14: ffff888048ceb558 R15: ffff88800c857180 > FS: 00007f0e798e9700(0000) GS:ffff88806cf00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000558bbbc7d898 CR3: 0000000048fb6000 CR4: 0000000000350ee0 > Call Trace: > __refcount_sub_and_test include/linux/refcount.h:283 [inline] > __refcount_dec_and_test include/linux/refcount.h:315 [inline] > refcount_dec_and_test include/linux/refcount.h:333 [inline] > io_put_req+0xc6/0x100 fs/io_uring.c:2220 > __io_queue_sqe+0x2b1/0xd00 fs/io_uring.c:6358 > io_queue_sqe+0x5bc/0x1020 fs/io_uring.c:6403 > io_queue_link_head fs/io_uring.c:6414 [inline] > io_submit_sqe fs/io_uring.c:6455 [inline] > io_submit_sqes+0x17b5/0x2310 fs/io_uring.c:6700 > __do_sys_io_uring_enter+0x1092/0x1910 fs/io_uring.c:9092 > do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x466609 > Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 bc ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f0e798e9188 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa > RAX: ffffffffffffffda RBX: 000000000056bf80 RCX: 0000000000466609 > RDX: 0000000000000000 RSI: 00000000000058ab RDI: 0000000000000004 > RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf80 > R13: 00007ffdbe4f1c5f R14: 00007f0e798e9300 R15: 0000000000022000 > irq event stamp: 1473 > hardirqs last enabled at (1483): [<ffffffff8128f5d9>] console_unlock+0x929/0xb30 kernel/printk/printk.c:2552 > hardirqs last disabled at (1494): [<ffffffff83c43a7b>] sysvec_apic_timer_interrupt+0xb/0xa0 arch/x86/kernel/apic/apic.c:1095 > softirqs last enabled at (1072): [<ffffffff83e00f92>] asm_call_irq_on_stack+0x12/0x20 > softirqs last disabled at (1067): [<ffffffff83e00f92>] asm_call_irq_on_stack+0x12/0x20 > > I have done a bisect and the commit causing this is: 0b2a990e5d2f ("io_uring: fix link timeout refs") > > The git bisect log is: > # bad: [71046eac2db9aeccf10763d034a1a123911c9a81] Linux 5.10.53 > # good: [2c85ebc57b3e1817b6ce1a6b703928e113a90442] Linux 5.10 > git bisect start 'v5.10.53' 'v5.10' > # good: [d29c38dd926d5aba65d177c0b99381ea632ff0a0] staging: rtl8192e: Change state information from u16 to u8 > git bisect good d29c38dd926d5aba65d177c0b99381ea632ff0a0 > # good: [b67c3d74adc3f7f832f57c170234bbe1fc69c87c] Revert "net: fujitsu: fix a potential NULL pointer dereference" > git bisect good b67c3d74adc3f7f832f57c170234bbe1fc69c87c > # bad: [f1f30b3373df2e5ab96dd3781df5c02e5366f845] mmc: usdhi6rol0: fix error return code in usdhi6_probe() > git bisect bad f1f30b3373df2e5ab96dd3781df5c02e5366f845 > # bad: [3d60457d74d9cc7b36f78f9cb74f29bc6182c1e8] cxgb4: fix endianness when flashing boot image > git bisect bad 3d60457d74d9cc7b36f78f9cb74f29bc6182c1e8 > # bad: [3a6b69221f96f87c680bbc9fba01db3415b18f27] drm/amdgpu: make sure we unpin the UVD BO > git bisect bad 3a6b69221f96f87c680bbc9fba01db3415b18f27 > # good: [65859eca4dff1af0db5e36d1cfbac15b834c6a65] Linux 5.10.42 > git bisect good 65859eca4dff1af0db5e36d1cfbac15b834c6a65 > # good: [a1bf16616d8351a2e79400d6d19608befb2ce1dd] ixgbe: add correct exception tracing for XDP > git bisect good a1bf16616d8351a2e79400d6d19608befb2ce1dd > # bad: [c5155c741a484e036e7997420559431a951f2106] wireguard: allowedips: allocate nodes in kmem_cache > git bisect bad c5155c741a484e036e7997420559431a951f2106 > # good: [3c23e23c7ad9844a645f4e2bd8ec34a0a2ee5514] riscv: vdso: fix and clean-up Makefile > git bisect good 3c23e23c7ad9844a645f4e2bd8ec34a0a2ee5514 > # bad: [74caf718cc7422a957aac381c73d798c0a999a65] Bluetooth: use correct lock to prevent UAF of hdev object > git bisect bad 74caf718cc7422a957aac381c73d798c0a999a65 > # bad: [58f4d45d8d4d391f60b6f0db6308df1994a265b3] drm/amdgpu/vcn3: add cancel_delayed_work_sync before power gate > git bisect bad 58f4d45d8d4d391f60b6f0db6308df1994a265b3 > # bad: [ec72cb50c1db39816eae7296686449bba8ca0b2e] io_uring: use better types for cflags > git bisect bad ec72cb50c1db39816eae7296686449bba8ca0b2e > # bad: [0b2a990e5d2f76d020cb840c456e6ec5f0c27530] io_uring: fix link timeout refs > git bisect bad 0b2a990e5d2f76d020cb840c456e6ec5f0c27530 > # first bad commit: [0b2a990e5d2f76d020cb840c456e6ec5f0c27530] io_uring: fix link timeout refs > > The mainline commit for the bad LTS commit is: > a298232ee6b9 ("io_uring: fix link timeout refs") and I have tested the > reproducer on mainline with 'a298232ee6b9' as HEAD and the issue is not > reproduced. I think we are missing some change in v5.10.y kernel which > was missed while the mainline fix was backported to LTS. > > I can reproduce the crash using syzkaller and will be happy to test any > patch for this. > > > -- > Regards > Sudip > -- Pavel Begunkov ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: use-after-free" with v5.10.y caused by backport of a298232ee6b9 ("io_uring: fix link timeout refs") 2021-07-26 10:57 ` Pavel Begunkov @ 2021-07-26 11:08 ` Greg Kroah-Hartman 2021-07-26 12:44 ` Sudip Mukherjee 0 siblings, 1 reply; 5+ messages in thread From: Greg Kroah-Hartman @ 2021-07-26 11:08 UTC (permalink / raw) To: Pavel Begunkov; +Cc: Sudip Mukherjee, stable, Jens Axboe, Sasha Levin On Mon, Jul 26, 2021 at 11:57:22AM +0100, Pavel Begunkov wrote: > On 7/26/21 11:29 AM, Sudip Mukherjee wrote: > > Hi Pavel, > > > > We had been running syzkaller on v5.10.y and a "use after free" is being > > reported for v5.10.43+ kernels. > > "... # 5.12+", weird, but perhaps due to dependencies. > Thanks for letting know. > > > Greg, Sasha, should be same as reported for 5.12 > > https://www.spinics.net/lists/stable/msg485116.html > > Can you try to apply it to 5.10 or should I resend? I just tried applying those patches and they did not work. So can you provide some new backports? thanks, greg k-h ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: use-after-free" with v5.10.y caused by backport of a298232ee6b9 ("io_uring: fix link timeout refs") 2021-07-26 11:08 ` Greg Kroah-Hartman @ 2021-07-26 12:44 ` Sudip Mukherjee 2021-07-26 12:53 ` Pavel Begunkov 0 siblings, 1 reply; 5+ messages in thread From: Sudip Mukherjee @ 2021-07-26 12:44 UTC (permalink / raw) To: Greg Kroah-Hartman; +Cc: Pavel Begunkov, stable, Jens Axboe, Sasha Levin [-- Attachment #1: Type: text/plain, Size: 843 bytes --] Hi Greg, On Mon, Jul 26, 2021 at 01:08:38PM +0200, Greg Kroah-Hartman wrote: > On Mon, Jul 26, 2021 at 11:57:22AM +0100, Pavel Begunkov wrote: > > On 7/26/21 11:29 AM, Sudip Mukherjee wrote: > > > Hi Pavel, > > > > > > We had been running syzkaller on v5.10.y and a "use after free" is being > > > reported for v5.10.43+ kernels. > > > > "... # 5.12+", weird, but perhaps due to dependencies. > > Thanks for letting know. > > > > > > Greg, Sasha, should be same as reported for 5.12 > > > > https://www.spinics.net/lists/stable/msg485116.html > > > > Can you try to apply it to 5.10 or should I resend? > > I just tried applying those patches and they did not work. So can you > provide some new backports? Here is the backport for v5.10.y. I have also tested these with the syzkaller repro and the issue is fixed. -- Regards Sudip [-- Attachment #2: 0001-io_uring-put-link-timeout-req-consistently.patch --] [-- Type: text/x-diff, Size: 1961 bytes --] From bd136e16d2f1b5480c60f4e78f18727d568c7d86 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov <asml.silence@gmail.com> Date: Thu, 1 Apr 2021 15:43:59 +0100 Subject: [PATCH 1/2] io_uring: put link timeout req consistently commit df9727affa058f4f18e388b30247650f8ae13cd8 upstream Don't put linked timeout req in io_async_find_and_cancel() but do it in io_link_timeout_fn(), so we have only one point for that and won't have to do it differently as it's now (put vs put_deferred). Btw, improve a bit io_async_find_and_cancel()'s locking. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/d75b70957f245275ab7cba83e0ac9c1b86aae78a.1617287883.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk> [sudip: adjust context] Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> --- fs/io_uring.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 42153106b7bc..a6c9c55ca3a3 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5697,12 +5697,9 @@ static void io_async_find_and_cancel(struct io_ring_ctx *ctx, int ret; ret = io_async_cancel_one(ctx, (void *) (unsigned long) sqe_addr); - if (ret != -ENOENT) { - spin_lock_irqsave(&ctx->completion_lock, flags); - goto done; - } - spin_lock_irqsave(&ctx->completion_lock, flags); + if (ret != -ENOENT) + goto done; ret = io_timeout_cancel(ctx, sqe_addr); if (ret != -ENOENT) goto done; @@ -5717,7 +5714,6 @@ static void io_async_find_and_cancel(struct io_ring_ctx *ctx, if (ret < 0) req_set_fail_links(req); - io_put_req(req); } static int io_async_cancel_prep(struct io_kiocb *req, @@ -6263,8 +6259,8 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer) io_put_req_deferred(req, 1); } else { io_cqring_add_event(req, -ETIME, 0); - io_put_req_deferred(req, 1); } + io_put_req_deferred(req, 1); return HRTIMER_NORESTART; } -- 2.30.2 [-- Attachment #3: 0002-io_uring-fix-link-timeout-refs.patch --] [-- Type: text/x-diff, Size: 2031 bytes --] From b901fb09894731c4ad84a359509508eff50a4920 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov <asml.silence@gmail.com> Date: Fri, 7 May 2021 21:06:38 +0100 Subject: [PATCH 2/2] io_uring: fix link timeout refs commit a298232ee6b9a1d5d732aa497ff8be0d45b5bd82 upstream WARNING: CPU: 0 PID: 10242 at lib/refcount.c:28 refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28 RIP: 0010:refcount_warn_saturate+0x15b/0x1a0 lib/refcount.c:28 Call Trace: __refcount_sub_and_test include/linux/refcount.h:283 [inline] __refcount_dec_and_test include/linux/refcount.h:315 [inline] refcount_dec_and_test include/linux/refcount.h:333 [inline] io_put_req fs/io_uring.c:2140 [inline] io_queue_linked_timeout fs/io_uring.c:6300 [inline] __io_queue_sqe+0xbef/0xec0 fs/io_uring.c:6354 io_submit_sqe fs/io_uring.c:6534 [inline] io_submit_sqes+0x2bbd/0x7c50 fs/io_uring.c:6660 __do_sys_io_uring_enter fs/io_uring.c:9240 [inline] __se_sys_io_uring_enter+0x256/0x1d60 fs/io_uring.c:9182 io_link_timeout_fn() should put only one reference of the linked timeout request, however in case of racing with the master request's completion first io_req_complete() puts one and then io_put_req_deferred() is called. Cc: stable@vger.kernel.org # 5.12+ Fixes: 9ae1f8dd372e0 ("io_uring: fix inconsistent lock state") Reported-by: syzbot+a2910119328ce8e7996f@syzkaller.appspotmail.com Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/ff51018ff29de5ffa76f09273ef48cb24c720368.1620417627.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> --- fs/io_uring.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index a6c9c55ca3a3..1a5951fbc763 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -6260,7 +6260,6 @@ static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer) } else { io_cqring_add_event(req, -ETIME, 0); } - io_put_req_deferred(req, 1); return HRTIMER_NORESTART; } -- 2.30.2 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: use-after-free" with v5.10.y caused by backport of a298232ee6b9 ("io_uring: fix link timeout refs") 2021-07-26 12:44 ` Sudip Mukherjee @ 2021-07-26 12:53 ` Pavel Begunkov 0 siblings, 0 replies; 5+ messages in thread From: Pavel Begunkov @ 2021-07-26 12:53 UTC (permalink / raw) To: Sudip Mukherjee, Greg Kroah-Hartman; +Cc: stable, Jens Axboe, Sasha Levin On 7/26/21 1:44 PM, Sudip Mukherjee wrote: > Hi Greg, > > On Mon, Jul 26, 2021 at 01:08:38PM +0200, Greg Kroah-Hartman wrote: >> On Mon, Jul 26, 2021 at 11:57:22AM +0100, Pavel Begunkov wrote: >>> On 7/26/21 11:29 AM, Sudip Mukherjee wrote: >>>> Hi Pavel, >>>> >>>> We had been running syzkaller on v5.10.y and a "use after free" is being >>>> reported for v5.10.43+ kernels. >>> >>> "... # 5.12+", weird, but perhaps due to dependencies. >>> Thanks for letting know. >>> >>> >>> Greg, Sasha, should be same as reported for 5.12 >>> >>> https://www.spinics.net/lists/stable/msg485116.html >>> >>> Can you try to apply it to 5.10 or should I resend? >> >> I just tried applying those patches and they did not work. So can you >> provide some new backports? > > Here is the backport for v5.10.y. I have also tested these with the > syzkaller repro and the issue is fixed. Thanks trying out, but it should be leaking requests (rarely), because io_cqring_add_event() doesn't put a ref unlike io_req_complete_post() from the original patch. I'll get to it today double checking refcounting. -- Pavel Begunkov ^ permalink raw reply [flat|nested] 5+ messages in thread
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2021-07-26 10:29 use-after-free" with v5.10.y caused by backport of a298232ee6b9 ("io_uring: fix link timeout refs") Sudip Mukherjee
2021-07-26 10:57 ` Pavel Begunkov
2021-07-26 11:08 ` Greg Kroah-Hartman
2021-07-26 12:44 ` Sudip Mukherjee
2021-07-26 12:53 ` Pavel Begunkov
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