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[openwrt/staging/chunkeey.git] / tools / dosfstools / patches / 0012-fsck.fat-Fix-read-beyond-end-of-array-on-FAT12.patch
1 From a41fc323f2ef38f884954a4ba3773a296fd809f8 Mon Sep 17 00:00:00 2001
2 From: Andreas Bombe <aeb@debian.org>
3 Date: Wed, 11 Mar 2015 21:45:04 +0100
4 Subject: [PATCH 12/14] fsck.fat: Fix read beyond end of array on FAT12
5
6 When a FAT12 filesystem contains an odd number of clusters, setting the
7 last cluster with set_fat() will trigger a read of the next entry,
8 which does not exist in the fat array allocated for this.
9
10 Round up the allocation to an even number of FAT entries for FAT12 so
11 that this is fixed without introducing special casing in get_fat().
12
13 Signed-off-by: Andreas Bombe <aeb@debian.org>
14 ---
15 src/fat.c | 14 +++++++++++---
16 1 file changed, 11 insertions(+), 3 deletions(-)
17
18 diff --git a/src/fat.c b/src/fat.c
19 index 027c586..5a92f56 100644
20 --- a/src/fat.c
21 +++ b/src/fat.c
22 @@ -80,7 +80,7 @@ void get_fat(FAT_ENTRY * entry, void *fat, uint32_t cluster, DOS_FS * fs)
23 */
24 void read_fat(DOS_FS * fs)
25 {
26 - int eff_size;
27 + int eff_size, alloc_size;
28 uint32_t i;
29 void *first, *second = NULL;
30 int first_ok, second_ok;
31 @@ -96,10 +96,18 @@ void read_fat(DOS_FS * fs)
32
33 total_num_clusters = fs->clusters + 2UL;
34 eff_size = (total_num_clusters * fs->fat_bits + 7) / 8ULL;
35 - first = alloc(eff_size);
36 +
37 + if (fs->fat_bits != 12)
38 + alloc_size = eff_size;
39 + else
40 + /* round up to an even number of FAT entries to avoid special
41 + * casing the last entry in get_fat() */
42 + alloc_size = (total_num_clusters * 12 + 23) / 24 * 3;
43 +
44 + first = alloc(alloc_size);
45 fs_read(fs->fat_start, eff_size, first);
46 if (fs->nfats > 1) {
47 - second = alloc(eff_size);
48 + second = alloc(alloc_size);
49 fs_read(fs->fat_start + fs->fat_size, eff_size, second);
50 }
51 if (second && memcmp(first, second, eff_size) != 0) {
52 --
53 1.9.1
54