5:32 a.m.
After porting my wayland compositor to io_uring, I noticed that my logs
were getting spammed with the following messages (tested with 5.17.7 and
5.18.0-rc7):
WARNING: CPU: 10 PID: 983 at kernel/auditsc.c:2041 __audit_syscall_entry+0x1>
Modules linked in: vrf wireguard curve25519_x86_64 libchacha20poly1305 chach>
ipmi_msghandler crypto_user ip_tables x_tables ext4 crc32c_generic crc16 mb>
CPU: 10 PID: 983 Comm: jay Tainted: G W 5.18.0-rc7-dirty #5 1>
Hardware name: Gigabyte Technology Co., Ltd. B450M DS3H/B450M DS3H-CF, BIOS >
RIP: 0010:__audit_syscall_entry+0x111/0x140
Code: e8 24 69 ff ff 48 8b 34 24 48 8b 54 24 08 85 c0 48 8b 4c 24 10 4c 8b 4>
RSP: 0018:ffffa6e480887de8 EFLAGS: 00010202
RAX: 0000000000000000 RBX: ffff969c92f22400 RCX: 0000000000000001
RDX: 0000000000000001 RSI: 0000000000000007 RDI: ffff969c8fa4c080
RBP: 00000000000001aa R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000001 R12: 00000000000001aa
R13: ffffa6e480887f58 R14: 00000000000001aa R15: 0000000000000000
FS: 00007fefe020f040(0000) GS:ffff96a39ea80000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fefac429000 CR3: 0000000103674000 CR4: 00000000003506e0
Call Trace:
<TASK>
? get_signal+0x8d/0x990
syscall_trace_enter.constprop.0+0x121/0x1a0
do_syscall_64+0x36/0x80
? arch_do_signal_or_restart+0x44/0x750
? syscall_exit_to_user_mode+0x22/0x40
? exit_to_user_mode_prepare+0xd3/0x140
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fefe0d0b67d
Code: 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 4>
RSP: 002b:00007fff383a6c58 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
RAX: ffffffffffffffda RBX: 00005595f1c25e00 RCX: 00007fefe0d0b67d
RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000007
RBP: 00005595f1c1b700 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000005 R14: 00005595f1c21f60 R15: 0000000000000001
</TASK>
---[ end trace 0000000000000000 ]---
audit: unrecoverable error in audit_syscall_entry()
I traced this to the context not being reset after audit_uring_entry if
the created context was a dummy context. I am surprised that I would be
the first one to find this problem but maybe io_uring is rarely used on
systems where auditing is enabled or a recent kernel change elsewhere
caused this problem to surface.
Julian Orth (1):
audit,io_uring,io-wq: call __audit_uring_exit for dummy contexts
include/linux/audit.h | 2 +-
kernel/auditsc.c | 6 ++++++
2 files changed, 7 insertions(+), 1 deletion(-)
--
2.36.1
5:32 a.m.
New subject: [PATCH 1/1] audit, io_uring, io-wq: call __audit_uring_exit for dummy contexts
Not calling the function for dummy contexts will cause the context to
not be reset. During the next syscall, this will cause an error in
__audit_syscall_entry:
WARN_ON(context->context != AUDIT_CTX_UNUSED);
WARN_ON(context->name_count);
if (context->context != AUDIT_CTX_UNUSED || context->name_count) {
audit_panic("unrecoverable error in audit_syscall_entry()");
return;
}
These problematic dummy contexts are created via the following call
chain:
exit_to_user_mode_prepare
-> arch_do_signal_or_restart
-> get_signal
-> task_work_run
-> tctx_task_work
-> io_req_task_submit
-> io_issue_sqe
-> audit_uring_entry
Fixes: 5bd2182d58e9 ("audit,io_uring,io-wq: add some basic audit support to
io_uring")
Signed-off-by: Julian Orth <ju.orth(a)gmail.com>
---
include/linux/audit.h | 2 +-
kernel/auditsc.c | 6 ++++++
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/include/linux/audit.h b/include/linux/audit.h
index d06134ac6245..cece70231138 100644
--- a/include/linux/audit.h
+++ b/include/linux/audit.h
@@ -339,7 +339,7 @@ static inline void audit_uring_entry(u8 op)
}
static inline void audit_uring_exit(int success, long code)
{
- if (unlikely(!audit_dummy_context()))
+ if (unlikely(audit_context()))
__audit_uring_exit(success, code);
}
static inline void audit_syscall_entry(int major, unsigned long a0,
diff --git a/kernel/auditsc.c b/kernel/auditsc.c
index ea2ee1181921..f3a2abd6d1a1 100644
--- a/kernel/auditsc.c
+++ b/kernel/auditsc.c
@@ -1959,6 +1959,12 @@ void __audit_uring_exit(int success, long code)
{
struct audit_context *ctx = audit_context();
+ if (ctx->dummy) {
+ if (ctx->context != AUDIT_CTX_URING)
+ return;
+ goto out;
+ }
+
if (ctx->context == AUDIT_CTX_SYSCALL) {
/*
* NOTE: See the note in __audit_uring_entry() about the case
--
2.36.1
8:12 a.m.
New subject: [PATCH 1/1] audit,io_uring,io-wq: call __audit_uring_exit for dummy contexts
On Tue, May 17, 2022 at 6:33 AM Julian Orth <ju.orth(a)gmail.com> wrote:
Not calling the function for dummy contexts will cause the context to
not be reset. During the next syscall, this will cause an error in
__audit_syscall_entry:
WARN_ON(context->context != AUDIT_CTX_UNUSED);
WARN_ON(context->name_count);
if (context->context != AUDIT_CTX_UNUSED || context->name_count) {
audit_panic("unrecoverable error in audit_syscall_entry()");
return;
}
These problematic dummy contexts are created via the following call
chain:
exit_to_user_mode_prepare
-> arch_do_signal_or_restart
-> get_signal
-> task_work_run
-> tctx_task_work
-> io_req_task_submit
-> io_issue_sqe
-> audit_uring_entry
Fixes: 5bd2182d58e9 ("audit,io_uring,io-wq: add some basic audit support to
io_uring")
Signed-off-by: Julian Orth <ju.orth(a)gmail.com>
---
include/linux/audit.h | 2 +-
kernel/auditsc.c | 6 ++++++
2 files changed, 7 insertions(+), 1 deletion(-)
Hi Julian,
Thanks for the report and the patch too! I agree that it does seem a
little odd that we haven't seen this before, let me dig into this a
bit more today and respond back.
--
paul-moore.com
4:34 p.m.
New subject: [PATCH 1/1] audit,io_uring,io-wq: call __audit_uring_exit for dummy contexts
On Tue, May 17, 2022 at 9:12 AM Paul Moore <paul(a)paul-moore.com> wrote:
On Tue, May 17, 2022 at 6:33 AM Julian Orth <ju.orth(a)gmail.com>
wrote:
>
> Not calling the function for dummy contexts will cause the context to
> not be reset. During the next syscall, this will cause an error in
> __audit_syscall_entry:
>
> WARN_ON(context->context != AUDIT_CTX_UNUSED);
> WARN_ON(context->name_count);
> if (context->context != AUDIT_CTX_UNUSED || context->name_count) {
> audit_panic("unrecoverable error in
audit_syscall_entry()");
> return;
> }
>
> These problematic dummy contexts are created via the following call
> chain:
>
> exit_to_user_mode_prepare
> -> arch_do_signal_or_restart
> -> get_signal
> -> task_work_run
> -> tctx_task_work
> -> io_req_task_submit
> -> io_issue_sqe
> -> audit_uring_entry
>
> Fixes: 5bd2182d58e9 ("audit,io_uring,io-wq: add some basic audit support to
io_uring")
> Signed-off-by: Julian Orth <ju.orth(a)gmail.com>
> ---
> include/linux/audit.h | 2 +-
> kernel/auditsc.c | 6 ++++++
> 2 files changed, 7 insertions(+), 1 deletion(-)
Hi Julian,
Thanks for the report and the patch too! I agree that it does seem a
little odd that we haven't seen this before, let me dig into this a
bit more today and respond back.
The patch looks good to me, thanks again. I just merged this into the
audit/stable-5.18 branch and added a stable tag; assuming the test
runs go okay I'll send this up to Linus tomorrow.
--
paul-moore.com
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3 comments
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participants (2)
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Julian Orth -
Paul Moore