60 lines
2.3 KiB
Diff
60 lines
2.3 KiB
Diff
From 83a95bd8c8561875b948cadd417c653dbe7ef2e2 Mon Sep 17 00:00:00 2001
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From: Yuliy Pisetsky <ypisetsky@fb.com>
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Date: Thu, 01 Jan 2015 23:36:55 +0000
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Subject: grep -F: fix a heap buffer (read) overrun
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grep's read buffer is often filled to its full size, except when
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reading the final buffer of a file. In that case, the number of
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bytes read may be far less than the size of the buffer. However, for
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certain unusual pattern/text combinations, grep -F would mistakenly
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examine bytes in that uninitialized region of memory when searching
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for a match. With carefully chosen inputs, one can cause grep -F to
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read beyond the end of that buffer altogether. This problem arose via
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commit v2.18-90-g73893ff with the introduction of a more efficient
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heuristic using what is now the memchr_kwset function. The use of
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that function in bmexec_trans could leave TP much larger than EP,
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and the subsequent call to bm_delta2_search would mistakenly access
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beyond end of the main input read buffer.
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* src/kwset.c (bmexec_trans): When TP reaches or exceeds EP,
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do not call bm_delta2_search.
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* tests/kwset-abuse: New file.
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* tests/Makefile.am (TESTS): Add it.
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* THANKS.in: Update.
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* NEWS (Bug fixes): Mention it.
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Prior to this patch, this command would trigger a UMR:
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printf %0360db 0 | valgrind src/grep -F $(printf %019dXb 0)
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Use of uninitialised value of size 8
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at 0x4142BE: bmexec_trans (kwset.c:657)
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by 0x4143CA: bmexec (kwset.c:678)
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by 0x414973: kwsexec (kwset.c:848)
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by 0x414DC4: Fexecute (kwsearch.c:128)
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by 0x404E2E: grepbuf (grep.c:1238)
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by 0x4054BF: grep (grep.c:1417)
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by 0x405CEB: grepdesc (grep.c:1645)
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by 0x405EC1: grep_command_line_arg (grep.c:1692)
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by 0x4077D4: main (grep.c:2570)
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See the accompanying test for how to trigger the heap buffer overrun.
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Thanks to Nima Aghdaii for testing and finding numerous
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ways to break early iterations of this patch.
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Nix: @vcunat restricted this to the runtime code only to avoid needing autoreconfiguration.
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---
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diff --git a/src/kwset.c b/src/kwset.c
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index 4003c8d..376f7c3 100644
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--- a/src/kwset.c
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+++ b/src/kwset.c
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@@ -643,6 +643,8 @@ bmexec_trans (kwset_t kwset, char const *text, size_t size)
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if (! tp)
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return -1;
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tp++;
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+ if (ep <= tp)
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+ break;
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}
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}
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}
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