On Thu 2023-08-10 22:45:32, Kees Cook wrote:
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@suse.com Cc: Sergey Senozhatsky senozhatsky@chromium.org Cc: Steven Rostedt rostedt@goodmis.org Cc: John Ogness john.ogness@linutronix.de Reported-by: Vijay Balakrishna vijayb@linux.microsoft.com Closes: https://lore.kernel.org/lkml/d8bb1ec7-a4c5-43a2-9de0-9643a70b899f@linux.micr...
checkpatch.pl suggested that "Link:" should be used instead of "Closes:".
Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook keescook@chromium.org
Reviewed-by: Petr Mladek pmladek@suse.com
Thanks a lot for tracking this down.
The patch has been comitted into printk/linux.git, branch for-6.6.
I though about pushing it for 5.5-rc7. But it is pretty old issue. It does not break the system. I wanted to give it some spin in linux-next. And I leave for vacation on Thursday. I will not have internet connection until Aug 28.
Best Regards, Petr