4.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Theodore Ts'o tytso@mit.edu
commit 5369a762c882c0b6e9599e4ebbb3a9ba9eee7e2d upstream.
In theory this should have been caught earlier when the xattr list was verified, but in case it got missed, it's simple enough to add check to make sure we don't overrun the xattr buffer.
This addresses CVE-2018-10879.
https://bugzilla.kernel.org/show_bug.cgi?id=200001
Signed-off-by: Theodore Ts'o tytso@mit.edu Reviewed-by: Andreas Dilger adilger@dilger.ca [bwh: Backported to 3.16: - Add inode parameter to ext4_xattr_set_entry() and update callers - Adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk [adjusted for 4.4 context] Signed-off-by: Daniel Rosenberg drosen@google.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/ext4/xattr.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)
--- a/fs/ext4/xattr.c +++ b/fs/ext4/xattr.c @@ -638,14 +638,20 @@ static size_t ext4_xattr_free_space(stru }
static int -ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s) +ext4_xattr_set_entry(struct ext4_xattr_info *i, struct ext4_xattr_search *s, + struct inode *inode) { - struct ext4_xattr_entry *last; + struct ext4_xattr_entry *last, *next; size_t free, min_offs = s->end - s->base, name_len = strlen(i->name);
/* Compute min_offs and last. */ last = s->first; - for (; !IS_LAST_ENTRY(last); last = EXT4_XATTR_NEXT(last)) { + for (; !IS_LAST_ENTRY(last); last = next) { + next = EXT4_XATTR_NEXT(last); + if ((void *)next >= s->end) { + EXT4_ERROR_INODE(inode, "corrupted xattr entries"); + return -EFSCORRUPTED; + } if (!last->e_value_block && last->e_value_size) { size_t offs = le16_to_cpu(last->e_value_offs); if (offs < min_offs) @@ -825,7 +831,7 @@ ext4_xattr_block_set(handle_t *handle, s ce = NULL; } ea_bdebug(bs->bh, "modifying in-place"); - error = ext4_xattr_set_entry(i, s); + error = ext4_xattr_set_entry(i, s, inode); if (!error) { if (!IS_LAST_ENTRY(s->first)) ext4_xattr_rehash(header(s->base), @@ -875,7 +881,7 @@ ext4_xattr_block_set(handle_t *handle, s s->end = s->base + sb->s_blocksize; }
- error = ext4_xattr_set_entry(i, s); + error = ext4_xattr_set_entry(i, s, inode); if (error == -EFSCORRUPTED) goto bad_block; if (error) @@ -1037,7 +1043,7 @@ int ext4_xattr_ibody_inline_set(handle_t
if (EXT4_I(inode)->i_extra_isize == 0) return -ENOSPC; - error = ext4_xattr_set_entry(i, s); + error = ext4_xattr_set_entry(i, s, inode); if (error) { if (error == -ENOSPC && ext4_has_inline_data(inode)) { @@ -1049,7 +1055,7 @@ int ext4_xattr_ibody_inline_set(handle_t error = ext4_xattr_ibody_find(inode, i, is); if (error) return error; - error = ext4_xattr_set_entry(i, s); + error = ext4_xattr_set_entry(i, s, inode); } if (error) return error; @@ -1075,7 +1081,7 @@ static int ext4_xattr_ibody_set(handle_t
if (EXT4_I(inode)->i_extra_isize == 0) return -ENOSPC; - error = ext4_xattr_set_entry(i, s); + error = ext4_xattr_set_entry(i, s, inode); if (error) return error; header = IHDR(inode, ext4_raw_inode(&is->iloc));