Yuliy Pisetsky reports: rep -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) External references: http://git.savannah.gnu.org/cgit/grep.git/commit/?id=83a95bd8c8561875b948cadd417c653dbe7ef2e2
*** This bug has been marked as a duplicate of bug 1183651 ***