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47 lines
1.7 KiB
47 lines
1.7 KiB
1 month ago
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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
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From: Daniel Axtens <dja@axtens.net>
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Date: Tue, 8 Mar 2022 18:17:03 +1100
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Subject: [PATCH] net/http: Fix OOB write for split http headers
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GRUB has special code for handling an http header that is split
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across two packets.
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The code tracks the end of line by looking for a "\n" byte. The
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code for split headers has always advanced the pointer just past the
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end of the line, whereas the code that handles unsplit headers does
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not advance the pointer. This extra advance causes the length to be
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one greater, which breaks an assumption in parse_line(), leading to
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it writing a NUL byte one byte past the end of the buffer where we
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reconstruct the line from the two packets.
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It's conceivable that an attacker controlled set of packets could
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cause this to zero out the first byte of the "next" pointer of the
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grub_mm_region structure following the current_line buffer.
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Do not advance the pointer in the split header case.
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Fixes: CVE-2022-28734
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Signed-off-by: Daniel Axtens <dja@axtens.net>
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Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
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(cherry picked from commit e9fb459638811c12b0989dbf64e3e124974ef617)
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---
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grub-core/net/http.c | 4 +---
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1 file changed, 1 insertion(+), 3 deletions(-)
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diff --git a/grub-core/net/http.c b/grub-core/net/http.c
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index 19cb8768e3..58546739a2 100644
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--- a/grub-core/net/http.c
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+++ b/grub-core/net/http.c
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@@ -193,9 +193,7 @@ http_receive (grub_net_tcp_socket_t sock __attribute__ ((unused)),
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int have_line = 1;
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char *t;
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ptr = grub_memchr (nb->data, '\n', nb->tail - nb->data);
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- if (ptr)
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- ptr++;
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- else
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+ if (ptr == NULL)
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{
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have_line = 0;
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ptr = (char *) nb->tail;
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