This is a note to let you know that I've just added the patch titled
printk: ringbuffer: Fix truncating buffer size min_t cast
to the 5.15-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:
printk-ringbuffer-fix-truncating-buffer-size-min_t-cast.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 53e9e33ede37a247d926db5e4a9e56b55204e66c Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@xxxxxxxxxxxx>
Date: Thu, 10 Aug 2023 22:45:32 -0700
Subject: printk: ringbuffer: Fix truncating buffer size min_t cast
From: Kees Cook <keescook@xxxxxxxxxxxx>
commit 53e9e33ede37a247d926db5e4a9e56b55204e66c upstream.
If an output buffer size exceeded U16_MAX, the min_t(u16, ...) cast in
copy_data() was causing writes to truncate. This manifested as output
bytes being skipped, seen as %NUL bytes in pstore dumps when the available
record size was larger than 65536. Fix the cast to no longer truncate
the calculation.
Cc: Petr Mladek <pmladek@xxxxxxxx>
Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reported-by: Vijay Balakrishna <vijayb@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/lkml/d8bb1ec7-a4c5-43a2-9de0-9643a70b899f@xxxxxxxxxxxxxxxxxxx/
Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Tested-by: Vijay Balakrishna <vijayb@xxxxxxxxxxxxxxxxxxx>
Tested-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx> # Steam Deck
Reviewed-by: Tyler Hicks (Microsoft) <code@xxxxxxxxxxx>
Tested-by: Tyler Hicks (Microsoft) <code@xxxxxxxxxxx>
Reviewed-by: John Ogness <john.ogness@xxxxxxxxxxxxx>
Reviewed-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Reviewed-by: Petr Mladek <pmladek@xxxxxxxx>
Signed-off-by: Petr Mladek <pmladek@xxxxxxxx>
Link: https://lore.kernel.org/r/20230811054528.never.165-kees@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/printk/printk_ringbuffer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -1724,7 +1724,7 @@ static bool copy_data(struct prb_data_ri
if (!buf || !buf_size)
return true;
- data_size = min_t(u16, buf_size, len);
+ data_size = min_t(unsigned int, buf_size, len);
memcpy(&buf[0], data, data_size); /* LMM(copy_data:A) */
return true;
Patches currently in stable-queue which might be from keescook@xxxxxxxxxxxx are
queue-5.15/selftests-harness-actually-report-skip-for-signal-te.patch
queue-5.15/arm-ptrace-restore-syscall-restart-tracing.patch
queue-5.15/printk-ringbuffer-fix-truncating-buffer-size-min_t-cast.patch
queue-5.15/arm-ptrace-restore-syscall-skipping-for-tracers.patch
queue-5.15/wifi-brcmfmac-fix-field-spanning-write-in-brcmf_scan.patch
