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72 lines
2.6 KiB
72 lines
2.6 KiB
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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diff --git a/src/regex/regexec.c b/src/regex/regexec.c
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index 16c5d0a..dd52319 100644
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--- a/src/regex/regexec.c
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+++ b/src/regex/regexec.c
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@@ -34,6 +34,7 @@
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#include <wchar.h>
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#include <wctype.h>
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#include <limits.h>
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+#include <stdint.h>
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#include <regex.h>
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@@ -206,11 +207,24 @@ tre_tnfa_run_parallel(const tre_tnfa_t *tnfa, const void *string,
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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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+ goto error_exit;
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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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+ goto error_exit;
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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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+ goto error_exit;
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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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@@ -221,10 +235,9 @@ tre_tnfa_run_parallel(const tre_tnfa_t *tnfa, const void *string,
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+ (rbytes + xbytes * tnfa->num_states) * 2 + tbytes + pbytes;
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/* Allocate the memory. */
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- buf = xmalloc((unsigned)total_bytes);
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+ buf = calloc(total_bytes, 1);
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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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/* Get the various pointers within tmp_buf (properly aligned). */
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tmp_tags = (void *)buf;
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--
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cgit v0.11.2
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