36 lines
1.5 KiB
Diff
36 lines
1.5 KiB
Diff
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From b667237b3a84f601ef5a707ce8eb861c3a5002d3 Mon Sep 17 00:00:00 2001
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From: Tobias Brunner <tobias@strongswan.org>
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Date: Tue, 28 Sep 2021 19:38:22 +0200
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Subject: [PATCH] cert-cache: Prevent crash due to integer overflow/sign change
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random() allocates values in the range [0, RAND_MAX], with RAND_MAX usually
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equaling INT_MAX = 2^31-1. Previously, values between 0 and 31 were added
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directly to that offset before applying`% CACHE_SIZE` to get an index into
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the cache array. If the random value was very high, this resulted in an
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integer overflow and a negative index value and, therefore, an out-of-bounds
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access of the array and in turn dereferencing invalid pointers when trying
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to acquire the read lock. This most likely results in a segmentation fault.
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Fixes: 764e8b2211ce ("reimplemented certificate cache")
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Fixes: CVE-2021-41991
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---
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src/libstrongswan/credentials/sets/cert_cache.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/src/libstrongswan/credentials/sets/cert_cache.c b/src/libstrongswan/credentials/sets/cert_cache.c
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index f1579c60a9bc..ceebb3843725 100644
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--- a/src/libstrongswan/credentials/sets/cert_cache.c
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+++ b/src/libstrongswan/credentials/sets/cert_cache.c
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@@ -151,7 +151,7 @@ static void cache(private_cert_cache_t *this,
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for (try = 0; try < REPLACE_TRIES; try++)
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{
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/* replace a random relation */
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- offset = random();
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+ offset = random() % CACHE_SIZE;
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for (i = 0; i < CACHE_SIZE; i++)
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{
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rel = &this->relations[(i + offset) % CACHE_SIZE];
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--
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2.25.1
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