74 lines
2.7 KiB
Diff
74 lines
2.7 KiB
Diff
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From c3edc06d1e1360f3570db9155d6b318ae0d0f0f7 Mon Sep 17 00:00:00 2001
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From: Rich Felker <dalias@aerifal.cx>
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Date: Thu, 6 Oct 2016 18:34:58 -0400
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Subject: fix missing integer overflow checks in regexec buffer size
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computations
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most of the possible overflows were already ruled out in practice by
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regcomp having already succeeded performing larger allocations.
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however at least the num_states*num_tags multiplication can clearly
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overflow in practice. for safety, check them all, and use the proper
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type, size_t, rather than int.
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also improve comments, use calloc in place of malloc+memset, and
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remove bogus casts.
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---
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src/regex/regexec.c | 23 ++++++++++++++++++-----
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1 file changed, 18 insertions(+), 5 deletions(-)
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Note: patch was modified to apply to tre, parts were taken from
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https://github.com/laurikari/tre/issues/37
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--- a/lib/tre-match-parallel.c
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+++ b/lib/tre-match-parallel.c
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@@ -59,6 +59,7 @@ char *alloca ();
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#ifdef HAVE_MALLOC_H
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#include <malloc.h>
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#endif /* HAVE_MALLOC_H */
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+#include <stdint.h>
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#include "tre-internal.h"
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#include "tre-match-utils.h"
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@@ -150,11 +151,24 @@ tre_tnfa_run_parallel(const tre_tnfa_t *
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/* Allocate memory for temporary data required for matching. This needs to
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be done for every matching operation to be thread safe. This allocates
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- everything in a single large block from the stack frame using alloca()
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- or with malloc() if alloca is unavailable. */
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+ everything in a single large block with calloc(). */
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{
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- int tbytes, rbytes, pbytes, xbytes, total_bytes;
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+ size_t tbytes, rbytes, pbytes, xbytes, total_bytes;
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char *tmp_buf;
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+
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+ /* Ensure that tbytes and xbytes*num_states cannot overflow, and that
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+ * they don't contribute more than 1/8 of SIZE_MAX to total_bytes. */
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+ if (num_tags > SIZE_MAX/(8 * sizeof(int) * tnfa->num_states))
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+ return REG_BADPAT;
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+
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+ /* Likewise check rbytes. */
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+ if (tnfa->num_states+1 > SIZE_MAX/(8 * sizeof(*reach_next)))
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+ return REG_BADPAT;
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+
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+ /* Likewise check pbytes. */
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+ if (tnfa->num_states > SIZE_MAX/(8 * sizeof(*reach_pos)))
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+ return REG_BADPAT;
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+
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/* Compute the length of the block we need. */
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tbytes = sizeof(*tmp_tags) * num_tags;
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rbytes = sizeof(*reach_next) * (tnfa->num_states + 1);
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@@ -168,11 +182,11 @@ tre_tnfa_run_parallel(const tre_tnfa_t *
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#ifdef TRE_USE_ALLOCA
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buf = alloca(total_bytes);
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#else /* !TRE_USE_ALLOCA */
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- buf = xmalloc((unsigned)total_bytes);
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+ buf = xmalloc(total_bytes);
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#endif /* !TRE_USE_ALLOCA */
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if (buf == NULL)
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return REG_ESPACE;
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- memset(buf, 0, (size_t)total_bytes);
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+ memset(buf, 0, total_bytes);
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/* Get the various pointers within tmp_buf (properly aligned). */
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tmp_tags = (void *)buf;
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