From: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Subject: zram: off by one in read_block_state() 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 <dan.carpenter@xxxxxxxxxx> Cc: Minchan Kim <minchan@xxxxxxxxxx> Cc: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/block/zram/zram_drv.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/block/zram/zram_drv.c~zram-off-by-one-in-read_block_state +++ a/drivers/block/zram/zram_drv.c @@ -910,7 +910,7 @@ static ssize_t read_block_state(struct f 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; } _
