From 23def86bbf716681e4dc89c4dac52b0645f5227d Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 5 Nov 2021 13:45:12 -0700 Subject: [PATCH] zram: off by one in read_block_state() [ Upstream commit a88e03cf3d190cf46bc4063a9b7efe87590de5f4 ] snprintf() returns the number of bytes it would have printed if there were space. But it does not count the NUL terminator. So that means that if "count == copied" then this has already overflowed by one character. This bug likely isn't super harmful in real life. Link: https://lkml.kernel.org/r/20210916130404.GA25094@kili Fixes: c0265342bff4 ("zram: introduce zram memory tracking") Signed-off-by: Dan Carpenter Cc: Minchan Kim Cc: Sergey Senozhatsky Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- drivers/block/zram/zram_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index 719c6b7741af..1cc9b67e9bca 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -901,7 +901,7 @@ static ssize_t read_block_state(struct file *file, char __user *buf, zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.', zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.'); - if (count < copied) { + if (count <= copied) { zram_slot_unlock(zram, index); break; }