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ext4: add corruption check in ext4_xattr_set_entry() 

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>
Cc: stable@kernel.org
This commit is contained in:
Theodore Ts'o 2018-06-13 00:23:11 -04:00
parent 327eaf738f
commit 5369a762c8
1 changed files with 8 additions and 2 deletions
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10
fs/ext4/xattr.c
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@ -1560,7 +1560,7 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
handle_t *handle, struct inode *inode,
bool is_block)
{
struct ext4_xattr_entry *last;
struct ext4_xattr_entry *last, *next;
struct ext4_xattr_entry *here = s->here;
size_t min_offs = s->end - s->base, name_len = strlen(i->name);
int in_inode = i->in_inode;
@ -1595,7 +1595,13 @@ static int ext4_xattr_set_entry(struct ext4_xattr_info *i,
/* 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");
ret = -EFSCORRUPTED;
goto out;
}
if (!last->e_value_inum && last->e_value_size) {
size_t offs = le16_to_cpu(last->e_value_offs);
if (offs < min_offs)