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| author | Darrick J. Wong <darrick.wong@oracle.com> | 2019-02-13 20:15:17 +0100 |
|---|---|---|
| committer | Darrick J. Wong <darrick.wong@oracle.com> | 2019-02-14 18:36:52 +0100 |
| commit | 3b50086f0c0d78c144d9483fa292c1509c931b70 (patch) | |
| tree | 8691f3942583f0e06a09a942271f58711c8244fc /fs/xfs | |
| parent | xfs: compile time offset checks for common v4/v5 metadata (diff) | |
| download | linux-3b50086f0c0d78c144d9483fa292c1509c931b70.tar.xz linux-3b50086f0c0d78c144d9483fa292c1509c931b70.zip | |
xfs: don't overflow xattr listent buffer
For VFS listxattr calls, xfs_xattr_put_listent calls
__xfs_xattr_put_listent twice if it sees an attribute
"trusted.SGI_ACL_FILE": once for that name, and again for
"system.posix_acl_access". Unfortunately, if we happen to run out of
buffer space while emitting the first name, we set count to -1 (so that
we can feed ERANGE to the caller). The second invocation doesn't check that
the context parameters make sense and overwrites the byte before the
buffer, triggering a KASAN report:
==================================================================
BUG: KASAN: slab-out-of-bounds in strncpy+0xb3/0xd0
Write of size 1 at addr ffff88807fbd317f by task syz/1113
CPU: 3 PID: 1113 Comm: syz Not tainted 5.0.0-rc6-xfsx #rc6
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-1ubuntu1 04/01/2014
Call Trace:
dump_stack+0xcc/0x180
print_address_description+0x6c/0x23c
kasan_report.cold.3+0x1c/0x35
strncpy+0xb3/0xd0
__xfs_xattr_put_listent+0x1a9/0x2c0 [xfs]
xfs_attr_list_int_ilocked+0x11af/0x1800 [xfs]
xfs_attr_list_int+0x20c/0x2e0 [xfs]
xfs_vn_listxattr+0x225/0x320 [xfs]
listxattr+0x11f/0x1b0
path_listxattr+0xbd/0x130
do_syscall_64+0x139/0x560
While we're at it we add an assert to the other put_listent to avoid
this sort of thing ever happening to the attrlist_by_handle code.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/xfs')
| -rw-r--r-- | fs/xfs/xfs_attr_list.c | 1 | ||||
| -rw-r--r-- | fs/xfs/xfs_xattr.c | 3 |
2 files changed, 4 insertions, 0 deletions
diff --git a/fs/xfs/xfs_attr_list.c b/fs/xfs/xfs_attr_list.c index a58034049995..3d213a7394c5 100644 --- a/fs/xfs/xfs_attr_list.c +++ b/fs/xfs/xfs_attr_list.c @@ -555,6 +555,7 @@ xfs_attr_put_listent( attrlist_ent_t *aep; int arraytop; + ASSERT(!context->seen_enough); ASSERT(!(context->flags & ATTR_KERNOVAL)); ASSERT(context->count >= 0); ASSERT(context->count < (ATTR_MAX_VALUELEN/8)); diff --git a/fs/xfs/xfs_xattr.c b/fs/xfs/xfs_xattr.c index 63ee1d5bf1d7..9a63016009a1 100644 --- a/fs/xfs/xfs_xattr.c +++ b/fs/xfs/xfs_xattr.c @@ -129,6 +129,9 @@ __xfs_xattr_put_listent( char *offset; int arraytop; + if (context->count < 0 || context->seen_enough) + return; + if (!context->alist) goto compute_size; |