From 9f029f540c2f7e010e4922d44ba0dfd05da79f88 Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Fri, 6 Nov 2015 16:31:31 -0800 Subject: [PATCH] lib/hexdump.c: truncate output in case of overflow There is a classical off-by-one error in case when we try to place, for example, 1+1 bytes as hex in the buffer of size 6. The expected result is to get an output truncated, but in the reality we get 6 bytes filed followed by terminating NUL. Change the logic how we fill the output in case of byte dumping into limited space. This will follow the snprintf() behaviour by truncating output even on half bytes. Fixes: 114fc1afb2de (hexdump: make it return number of bytes placed in buffer) Signed-off-by: Andy Shevchenko Reported-by: Aaro Koskinen Tested-by: Aaro Koskinen Cc: Al Viro Cc: Catalin Marinas Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/hexdump.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/lib/hexdump.c b/lib/hexdump.c index 8d74c20d8595..992457b1284c 100644 --- a/lib/hexdump.c +++ b/lib/hexdump.c @@ -169,11 +169,15 @@ int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize, } } else { for (j = 0; j < len; j++) { - if (linebuflen < lx + 3) + if (linebuflen < lx + 2) goto overflow2; ch = ptr[j]; linebuf[lx++] = hex_asc_hi(ch); + if (linebuflen < lx + 2) + goto overflow2; linebuf[lx++] = hex_asc_lo(ch); + if (linebuflen < lx + 2) + goto overflow2; linebuf[lx++] = ' '; } if (j) -- 2.20.1