From: Yun Zhou Date: Sat, 26 Jun 2021 03:21:55 +0000 (+0800) Subject: seq_buf: Fix overflow in seq_buf_putmem_hex() X-Git-Tag: v4.19.198~121 X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1f4c6061fccee64b2072b28dfa3e93cf859c4c0a;p=users%2Fdwmw2%2Flinux.git seq_buf: Fix overflow in seq_buf_putmem_hex() commit d3b16034a24a112bb83aeb669ac5b9b01f744bb7 upstream. There's two variables being increased in that loop (i and j), and i follows the raw data, and j follows what is being written into the buffer. We should compare 'i' to MAX_MEMHEX_BYTES or compare 'j' to HEX_CHARS. Otherwise, if 'j' goes bigger than HEX_CHARS, it will overflow the destination buffer. Link: https://lore.kernel.org/lkml/20210625122453.5e2fe304@oasis.local.home/ Link: https://lkml.kernel.org/r/20210626032156.47889-1-yun.zhou@windriver.com Cc: stable@vger.kernel.org Fixes: 5e3ca0ec76fce ("ftrace: introduce the "hex" output method") Signed-off-by: Yun Zhou Signed-off-by: Steven Rostedt (VMware) Signed-off-by: Greg Kroah-Hartman --- diff --git a/lib/seq_buf.c b/lib/seq_buf.c index 97de70872c9e8..562e53c93b7b2 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -228,8 +228,10 @@ int seq_buf_putmem_hex(struct seq_buf *s, const void *mem, WARN_ON(s->size == 0); + BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS); + while (len) { - start_len = min(len, HEX_CHARS - 1); + start_len = min(len, MAX_MEMHEX_BYTES); #ifdef __BIG_ENDIAN for (i = 0, j = 0; i < start_len; i++) { #else