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authorKees Cook <keescook@chromium.org>2023-08-10 22:45:32 -0700
committerPetr Mladek <pmladek@suse.com>2023-08-14 13:05:22 +0200
commit53e9e33ede37a247d926db5e4a9e56b55204e66c (patch)
treeed369146574085fecd752919ec0a7bec0d7b874e /kernel
parentcd47fe860185a8d385bba693ab79497fdf12cd78 (diff)
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printk: ringbuffer: Fix truncating buffer size min_t cast
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> Link: https://lore.kernel.org/lkml/d8bb1ec7-a4c5-43a2-9de0-9643a70b899f@linux.microsoft.com/ Fixes: b6cf8b3f3312 ("printk: add lockless ringbuffer") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Tested-by: Vijay Balakrishna <vijayb@linux.microsoft.com> Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck Reviewed-by: Tyler Hicks (Microsoft) <code@tyhicks.com> Tested-by: Tyler Hicks (Microsoft) <code@tyhicks.com> Reviewed-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20230811054528.never.165-kees@kernel.org
Diffstat (limited to 'kernel')
-rw-r--r--kernel/printk/printk_ringbuffer.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c
index 2dc4d5a1f1ff..fde338606ce8 100644
--- a/kernel/printk/printk_ringbuffer.c
+++ b/kernel/printk/printk_ringbuffer.c
@@ -1735,7 +1735,7 @@ static bool copy_data(struct prb_data_ring *data_ring,
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;