| From f66e6ce4446738c2c7f43d41988a3eb73347e2f5 Mon Sep 17 00:00:00 2001 |
| From: Theodore Ts'o <tytso@mit.edu> |
| Date: Sat, 9 Aug 2014 12:24:54 -0400 |
| Subject: libext2fs: avoid buffer overflow if s_first_meta_bg is too big |
| |
| If s_first_meta_bg is greater than the of number block group |
| descriptor blocks, then reading or writing the block group descriptors |
| will end up overruning the memory buffer allocated for the |
| descriptors. Fix this by limiting first_meta_bg to no more than |
| fs->desc_blocks. This doesn't correct the bad s_first_meta_bg value, |
| but it avoids causing the e2fsprogs userspace programs from |
| potentially crashing. |
| |
| Fixes CVE-2015-0247 |
| Upstream-Status: Backport |
| |
| Signed-off-by: Theodore Ts'o <tytso@mit.edu> |
| Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com> |
| |
| diff --git a/lib/ext2fs/closefs.c b/lib/ext2fs/closefs.c |
| index 4599eef..1f99113 100644 |
| --- a/lib/ext2fs/closefs.c |
| +++ b/lib/ext2fs/closefs.c |
| @@ -344,9 +344,11 @@ errcode_t ext2fs_flush2(ext2_filsys fs, int flags) |
| * superblocks and group descriptors. |
| */ |
| group_ptr = (char *) group_shadow; |
| - if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) |
| + if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) { |
| old_desc_blocks = fs->super->s_first_meta_bg; |
| - else |
| + if (old_desc_blocks > fs->super->s_first_meta_bg) |
| + old_desc_blocks = fs->desc_blocks; |
| + } else |
| old_desc_blocks = fs->desc_blocks; |
| |
| ext2fs_numeric_progress_init(fs, &progress, NULL, |
| diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c |
| index a1a3517..ba501e6 100644 |
| --- a/lib/ext2fs/openfs.c |
| +++ b/lib/ext2fs/openfs.c |
| @@ -378,9 +378,11 @@ errcode_t ext2fs_open2(const char *name, const char *io_options, |
| #ifdef WORDS_BIGENDIAN |
| groups_per_block = EXT2_DESC_PER_BLOCK(fs->super); |
| #endif |
| - if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) |
| + if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) { |
| first_meta_bg = fs->super->s_first_meta_bg; |
| - else |
| + if (first_meta_bg > fs->desc_blocks) |
| + first_meta_bg = fs->desc_blocks; |
| + } else |
| first_meta_bg = fs->desc_blocks; |
| if (first_meta_bg) { |
| retval = io_channel_read_blk(fs->io, group_block + |
| -- |
| cgit v0.10.2 |
| |