From e0a1add063a657b98611c94debb3631b8ffa36fe Mon Sep 17 00:00:00 2001 From: Junling Zheng Date: Fri, 24 Apr 2015 11:24:04 +0800 Subject: [PATCH] Fix possible buffer overrun with invalid UTF-8 An out of bounds read access in the UTF-8 decoding can be triggered with a malformed file in the tool less. The access happens in the function is_utf8_well_formed due to a truncated multibyte character in the sample file. The bug does not crash less, it can only be made visible by running less with valgrind or compiling it with Address Sanitizer. Version 475 of less contains a fix for this issue. The file version.c contains some entry mentioning this issue (without any credit): - v475 3/2/15 Fix possible buffer overrun with invalid UTF-8 The fix is in the file line.c. We derive this patch from: https://blog.fuzzing-project.org/3-less-out-of-bounds-read-access-TFPA-0022014.html Thank Claire Robinson for validating it on Mageia 4 i586. Refer to: https://bugs.mageia.org/show_bug.cgi?id=15567 Upstream Status: Backported Signed-off-by: Junling Zheng --- line.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/line.c b/line.c index 89495a3..474be2c 100644 --- a/line.c +++ b/line.c @@ -807,7 +807,7 @@ pappend(c, pos) mbc_buf[mbc_buf_index++] = c; if (mbc_buf_index < mbc_buf_len) return (0); - if (is_utf8_well_formed(mbc_buf)) + if (is_utf8_well_formed(mbc_buf, mbc_buf_index)) r = do_append(get_wchar(mbc_buf), mbc_buf, mbc_pos); else /* Complete, but not shortest form, sequence. */ -- 1.9.1