linux-kernel - [PATCH 4.4 10/48] ext4: add corruption check in ext4_xattr_set

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20181018175428.537398160@linuxfoundation.org>
Date:   Thu, 18 Oct 2018 19:54:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Theodore Tso <tytso@....edu>,
        Andreas Dilger <adilger@...ger.ca>,
        Ben Hutchings <ben@...adent.org.uk>,
        Daniel Rosenberg <drosen@...gle.com>
Subject: [PATCH 4.4 10/48] ext4: add corruption check in ext4_xattr_set_entry()

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@....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@....edu>
Reviewed-by: Andreas Dilger <adilger@...ger.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@...adent.org.uk>
[adjusted for 4.4 context]
Signed-off-by: Daniel Rosenberg <drosen@...gle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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));