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grub2/SOURCES/0450-io-gzio-Add-init_dynam...

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Thu, 21 Jan 2021 00:05:58 +1100
Subject: [PATCH] io/gzio: Add init_dynamic_block() clean up if unpacking codes
fails
init_dynamic_block() didn't clean up gzio->tl and td in some error
paths. This left td pointing to part of tl. Then in grub_gzio_close(),
when tl was freed the storage for td would also be freed. The code then
attempts to free td explicitly, performing a UAF and then a double free.
Explicitly clean up tl and td in the error paths.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
---
grub-core/io/gzio.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/grub-core/io/gzio.c b/grub-core/io/gzio.c
index 6e9b9c936..97b34f885 100644
--- a/grub-core/io/gzio.c
+++ b/grub-core/io/gzio.c
@@ -953,7 +953,7 @@ init_dynamic_block (grub_gzio_t gzio)
if ((unsigned) i + j > n)
{
grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found");
- return;
+ goto fail;
}
while (j--)
ll[i++] = l;
@@ -966,7 +966,7 @@ init_dynamic_block (grub_gzio_t gzio)
if ((unsigned) i + j > n)
{
grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found");
- return;
+ goto fail;
}
while (j--)
ll[i++] = 0;
@@ -981,7 +981,7 @@ init_dynamic_block (grub_gzio_t gzio)
if ((unsigned) i + j > n)
{
grub_error (GRUB_ERR_BAD_COMPRESSED_DATA, "too many codes found");
- return;
+ goto fail;
}
while (j--)
ll[i++] = 0;
@@ -1019,6 +1019,12 @@ init_dynamic_block (grub_gzio_t gzio)
/* indicate we're now working on a block */
gzio->code_state = 0;
gzio->block_len++;
+ return;
+
+ fail:
+ huft_free (gzio->tl);
+ gzio->td = NULL;
+ gzio->tl = NULL;
}