From 8b7b2f4d24b53047a776987ab6c784fb8de45525 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 29 Nov 2023 16:18:44 +0000 Subject: [PATCH] printk: ringbuffer: Fix truncating buffer size min_t cast stable inclusion from stable-v5.10.192 commit 8c90c4e61929eb6af0b227497556a09e0691d2eb category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8KG4V Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c90c4e61929 -------------------------------- 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 Cc: Sergey Senozhatsky Cc: Steven Rostedt Cc: John Ogness Reported-by: Vijay Balakrishna 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 Tested-by: Vijay Balakrishna Tested-by: Guilherme G. Piccoli # Steam Deck Reviewed-by: Tyler Hicks (Microsoft) Tested-by: Tyler Hicks (Microsoft) Reviewed-by: John Ogness Reviewed-by: Sergey Senozhatsky Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/20230811054528.never.165-kees@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ye Weihua --- kernel/printk/printk_ringbuffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/printk/printk_ringbuffer.c b/kernel/printk/printk_ringbuffer.c index 617dd6358965..3e8214e9bf4a 100644 --- a/kernel/printk/printk_ringbuffer.c +++ b/kernel/printk/printk_ringbuffer.c @@ -1726,7 +1726,7 @@ 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; -- Gitee