36 lines
1.2 KiB
Diff
36 lines
1.2 KiB
Diff
From a886ea40a29a08954ff80772e267828a1d440cc9 Mon Sep 17 00:00:00 2001
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From: Eric Blake <eblake@redhat.com>
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Date: Fri, 13 Jan 2023 16:27:54 -0600
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Subject: [PATCH] output: Avoid tickling UBSAN with memcpy(dest, NULL, 0)
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Even though all libc handle it sanely (because size 0 says there is
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nothing to copy), NULL is not a valid source pointer per a strict
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reading of C, so UBSAN flags it:
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+output.c:511:9: runtime error: null pointer passed as argument 2, which is declared to never be null
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* src/output.c (make_room_for): Skip no-op memcpy.
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Fixes: https://savannah.gnu.org/support/index.php?110809
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Reported-by: Sam James
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---
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src/output.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/src/output.c b/src/output.c
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index 956089b1..6dc8280a 100644
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--- a/src/output.c
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+++ b/src/output.c
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@@ -508,7 +508,8 @@ make_room_for (int length)
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{
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char *buffer = output_diversion->u.buffer;
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output_diversion->u.buffer = xcharalloc ((size_t) wanted_size);
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- memcpy (output_diversion->u.buffer, buffer, output_diversion->used);
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+ if (output_diversion->used)
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+ memcpy (output_diversion->u.buffer, buffer, output_diversion->used);
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free (buffer);
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}
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--
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2.33.0
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