046693e14b
pixman < 0.42.2 is affected by an out-of-bounds write error in the
`rasterize_edges_8()` function due to an integer overflow in the
`pixman_sample_floor_y()` function.
For more information please check the upstream bug report [1].
This patch backports commit a1f88e842e02 ("Avoid integer overflow
leading to out-of-bounds write") [2] to fix CVE-2022-44638.
In order to test and validate the fix, a reproducer can be found in the
original bug report [3] and compiled with the following command:
$ gcc -o poc poc.c -ldl -fsanitize=address \
$(pkg-config --cflags --libs pixman-1)
[1] https://gitlab.freedesktop.org/pixman/pixman/-/issues/63
[2] a1f88e842e
[3] https://gitlab.freedesktop.org/pixman/pixman/uploads/a55795e36afc03445ed838b0fda786f9/poc.c
Resolves: https://issues.redhat.com/browse/RHEL-7854
30 lines
869 B
Diff
30 lines
869 B
Diff
From a1f88e842e0216a5b4df1ab023caebe33c101395 Mon Sep 17 00:00:00 2001
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From: Matt Turner <mattst88@gmail.com>
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Date: Wed, 2 Nov 2022 12:07:32 -0400
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Subject: [PATCH] Avoid integer overflow leading to out-of-bounds write
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Thanks to Maddie Stone and Google's Project Zero for discovering this
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issue, providing a proof-of-concept, and a great analysis.
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Closes: https://gitlab.freedesktop.org/pixman/pixman/-/issues/63
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---
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pixman/pixman-trap.c | 2 +-
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1 file changed, 1 insertion(+), 1 deletion(-)
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diff --git a/pixman/pixman-trap.c b/pixman/pixman-trap.c
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index 91766fd..7560405 100644
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--- a/pixman/pixman-trap.c
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+++ b/pixman/pixman-trap.c
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@@ -74,7 +74,7 @@ pixman_sample_floor_y (pixman_fixed_t y,
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if (f < Y_FRAC_FIRST (n))
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{
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- if (pixman_fixed_to_int (i) == 0x8000)
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+ if (pixman_fixed_to_int (i) == 0xffff8000)
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{
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f = 0; /* saturate */
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}
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--
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2.41.0
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