From 83a95bd8c8561875b948cadd417c653dbe7ef2e2 Mon Sep 17 00:00:00 2001 From: Yuliy Pisetsky Date: Thu, 01 Jan 2015 23:36:55 +0000 Subject: grep -F: fix a heap buffer (read) overrun grep's read buffer is often filled to its full size, except when reading the final buffer of a file. In that case, the number of bytes read may be far less than the size of the buffer. However, for certain unusual pattern/text combinations, grep -F would mistakenly examine bytes in that uninitialized region of memory when searching for a match. With carefully chosen inputs, one can cause grep -F to read beyond the end of that buffer altogether. This problem arose via commit v2.18-90-g73893ff with the introduction of a more efficient heuristic using what is now the memchr_kwset function. The use of that function in bmexec_trans could leave TP much larger than EP, and the subsequent call to bm_delta2_search would mistakenly access beyond end of the main input read buffer. * src/kwset.c (bmexec_trans): When TP reaches or exceeds EP, do not call bm_delta2_search. * tests/kwset-abuse: New file. * tests/Makefile.am (TESTS): Add it. * THANKS.in: Update. * NEWS (Bug fixes): Mention it. Prior to this patch, this command would trigger a UMR: printf %0360db 0 | valgrind src/grep -F $(printf %019dXb 0) Use of uninitialised value of size 8 at 0x4142BE: bmexec_trans (kwset.c:657) by 0x4143CA: bmexec (kwset.c:678) by 0x414973: kwsexec (kwset.c:848) by 0x414DC4: Fexecute (kwsearch.c:128) by 0x404E2E: grepbuf (grep.c:1238) by 0x4054BF: grep (grep.c:1417) by 0x405CEB: grepdesc (grep.c:1645) by 0x405EC1: grep_command_line_arg (grep.c:1692) by 0x4077D4: main (grep.c:2570) See the accompanying test for how to trigger the heap buffer overrun. Thanks to Nima Aghdaii for testing and finding numerous ways to break early iterations of this patch. --- diff --git a/NEWS b/NEWS index 975440d..3835d8d 100644 --- a/NEWS +++ b/NEWS @@ -2,6 +2,11 @@ GNU grep NEWS -*- outline -*- * Noteworthy changes in release ?.? (????-??-??) [?] +** Bug fixes + + grep no longer reads from uninitialized memory or from beyond the end + of the heap-allocated input buffer. + * Noteworthy changes in release 2.21 (2014-11-23) [stable] diff --git a/THANKS.in b/THANKS.in index aeaf516..624478d 100644 --- a/THANKS.in +++ b/THANKS.in @@ -62,6 +62,7 @@ Michael Aichlmayr mikla@nx.com Miles Bader miles@ccs.mt.nec.co.jp Mirraz Mirraz mirraz1@rambler.ru Nelson H. F. Beebe beebe@math.utah.edu +Nima Aghdaii naghdaii@fb.com Olaf Kirch okir@ns.lst.de Paul Kimoto kimoto@spacenet.tn.cornell.edu Péter Radics mitchnull@gmail.com diff --git a/src/kwset.c b/src/kwset.c index 4003c8d..376f7c3 100644 --- a/src/kwset.c +++ b/src/kwset.c @@ -643,6 +643,8 @@ bmexec_trans (kwset_t kwset, char const *text, size_t size) if (! tp) return -1; tp++; + if (ep <= tp) + break; } } } -- cgit v0.9.0.2