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| author | Theodore Ts'o <tytso@mit.edu> | 2014-08-09 12:24:54 -0400 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2014-08-10 16:20:59 -0400 |
| commit | f66e6ce4446738c2c7f43d41988a3eb73347e2f5 (patch) | |
| tree | a9e05d6bcc5b921222ff5929c7696d930ef46882 | |
| parent | f00948ad1df100c7d616ef6fbf7609329a2e4001 (diff) | |
| download | e2fsprogs-f66e6ce4446738c2c7f43d41988a3eb73347e2f5.tar.gz | |
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.
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
| -rw-r--r-- | lib/ext2fs/closefs.c | 6 | ||||
| -rw-r--r-- | lib/ext2fs/openfs.c | 6 |
2 files changed, 8 insertions, 4 deletions
diff --git a/lib/ext2fs/closefs.c b/lib/ext2fs/closefs.c index 4599eef5..1f991131 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 a1a35176..ba501e6a 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 + |