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Commit 290ab230 authored by Eric Biggers's avatar Eric Biggers Committed by Theodore Ts'o
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ext4: don't read out of bounds when checking for in-inode xattrs 



With i_extra_isize equal to or close to the available space, it was
possible for us to read past the end of the inode when trying to detect
or validate in-inode xattrs.  Fix this by checking for the needed extra
space first.

This patch shouldn't have any noticeable effect on
non-corrupted/non-malicious filesystems.

Signed-off-by: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Reviewed-by: default avatarAndreas Dilger <adilger@dilger.ca>
parent 2dc8d9e1

fs/ext4/inode.c

+3 −1
Original line number Diff line number Diff line
@@ -4527,7 +4527,9 @@ static inline void ext4_iget_extra_inode(struct inode *inode, 
{

	__le32 *magic = (void *)raw_inode +

			EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize;

	if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {

	if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize + sizeof(__le32) <=

	    EXT4_INODE_SIZE(inode->i_sb) &&

	    *magic == cpu_to_le32(EXT4_XATTR_MAGIC)) {

		ext4_set_inode_state(inode, EXT4_STATE_XATTR);

		ext4_find_inline_data_nolock(inode);

	} else

fs/ext4/xattr.c

+2 −3
Original line number Diff line number Diff line
@@ -231,13 +231,12 @@ static int 
__xattr_check_inode(struct inode *inode, struct ext4_xattr_ibody_header *header,

			 void *end, const char *function, unsigned int line)

{

	struct ext4_xattr_entry *entry = IFIRST(header);

	int error = -EFSCORRUPTED;



	if (((void *) header >= end) ||

	if (end - (void *)header < sizeof(*header) + sizeof(u32) ||

	    (header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)))

		goto errout;

	error = ext4_xattr_check_names(entry, end, entry);

	error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header));

errout:

	if (error)

		__ext4_error_inode(inode, function, line, 0,