This is a note to let you know that I've just added the patch titled
tracing: Fix null pointer dereference in tracing_err_log_open()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
tracing-fix-null-pointer-dereference-in-tracing_err_log_open.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 02b0095e2fbbc060560c1065f86a211d91e27b26 Mon Sep 17 00:00:00 2001
From: Mateusz Stachyra <m.stachyra@xxxxxxxxxxx>
Date: Tue, 4 Jul 2023 12:27:06 +0200
Subject: tracing: Fix null pointer dereference in tracing_err_log_open()
From: Mateusz Stachyra <m.stachyra@xxxxxxxxxxx>
commit 02b0095e2fbbc060560c1065f86a211d91e27b26 upstream.
Fix an issue in function 'tracing_err_log_open'.
The function doesn't call 'seq_open' if the file is opened only with
write permissions, which results in 'file->private_data' being left as null.
If we then use 'lseek' on that opened file, 'seq_lseek' dereferences
'file->private_data' in 'mutex_lock(&m->lock)', resulting in a kernel panic.
Writing to this node requires root privileges, therefore this bug
has very little security impact.
Tracefs node: /sys/kernel/tracing/error_log
Example Kernel panic:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000038
Call trace:
mutex_lock+0x30/0x110
seq_lseek+0x34/0xb8
__arm64_sys_lseek+0x6c/0xb8
invoke_syscall+0x58/0x13c
el0_svc_common+0xc4/0x10c
do_el0_svc+0x24/0x98
el0_svc+0x24/0x88
el0t_64_sync_handler+0x84/0xe4
el0t_64_sync+0x1b4/0x1b8
Code: d503201f aa0803e0 aa1f03e1 aa0103e9 (c8e97d02)
---[ end trace 561d1b49c12cf8a5 ]---
Kernel panic - not syncing: Oops: Fatal exception
Link: https://lore.kernel.org/linux-trace-kernel/20230703155237eucms1p4dfb6a19caa14c79eb6c823d127b39024@eucms1p4
Link: https://lore.kernel.org/linux-trace-kernel/20230704102706eucms1p30d7ecdcc287f46ad67679fc8491b2e0f@eucms1p3
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 8a062902be725 ("tracing: Add tracing error log")
Signed-off-by: Mateusz Stachyra <m.stachyra@xxxxxxxxxxx>
Suggested-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Acked-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/trace/trace.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -7263,7 +7263,7 @@ static const struct file_operations trac
.open = tracing_err_log_open,
.write = tracing_err_log_write,
.read = seq_read,
- .llseek = seq_lseek,
+ .llseek = tracing_lseek,
.release = tracing_err_log_release,
};
Patches currently in stable-queue which might be from m.stachyra@xxxxxxxxxxx are
queue-5.4/tracing-fix-null-pointer-dereference-in-tracing_err_log_open.patch
