diff options
| author | Chao Yu <yuchao0@huawei.com> | 2019-03-04 17:19:04 +0800 |
|---|---|---|
| committer | Jaegeuk Kim <jaegeuk@kernel.org> | 2019-03-12 19:02:26 -0700 |
| commit | dd6c89b5f2b93ceced4111e7b69d4efd8c312713 (patch) | |
| tree | 38e9e03aa5cd85dc7fcd0125a51097a3f7a44e8d /fs/f2fs/xattr.h | |
| parent | 70db5b04cbe19e5ae7e85ada2d3e82bcfdf90352 (diff) | |
f2fs: fix to do sanity check with inode.i_inline_xattr_size
As Paul Bandha reported in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=202709
When I run the poc on the mounted f2fs img I get a buffer overflow in
read_inline_xattr due to there being no sanity check on the value of
i_inline_xattr_size.
I created the img by just modifying the value of i_inline_xattr_size
in the inode:
i_name [test1.txt]
i_ext: fofs:0 blkaddr:0 len:0
i_extra_isize [0x 18 : 24]
i_inline_xattr_size [0x ffff : 65535]
i_addr[ofs] [0x 0 : 0]
mkdir /mnt/f2fs
mount ./f2fs1.img /mnt/f2fs
gcc poc.c -o poc
./poc
int main() {
int y = syscall(SYS_listxattr, "/mnt/f2fs/test1.txt", NULL, 0);
printf("ret %d", y);
printf("errno: %d\n", errno);
}
BUG: KASAN: slab-out-of-bounds in read_inline_xattr+0x18f/0x260
Read of size 262140 at addr ffff88011035efd8 by task f2fs1poc/3263
CPU: 0 PID: 3263 Comm: f2fs1poc Not tainted 4.18.0-custom #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014
Call Trace:
dump_stack+0x71/0xab
print_address_description+0x83/0x250
kasan_report+0x213/0x350
memcpy+0x1f/0x50
read_inline_xattr+0x18f/0x260
read_all_xattrs+0xba/0x190
f2fs_listxattr+0x9d/0x3f0
listxattr+0xb2/0xd0
path_listxattr+0x93/0xe0
do_syscall_64+0x9d/0x220
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Let's add sanity check for inode.i_inline_xattr_size during f2fs_iget()
to avoid this issue.
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'fs/f2fs/xattr.h')
| -rw-r--r-- | fs/f2fs/xattr.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/f2fs/xattr.h b/fs/f2fs/xattr.h index 67db134da0f5..9172ee082ca8 100644 --- a/fs/f2fs/xattr.h +++ b/fs/f2fs/xattr.h @@ -78,6 +78,12 @@ struct f2fs_xattr_entry { sizeof(struct f2fs_xattr_header) - \ sizeof(struct f2fs_xattr_entry)) +#define MAX_INLINE_XATTR_SIZE \ + (DEF_ADDRS_PER_INODE - \ + F2FS_TOTAL_EXTRA_ATTR_SIZE / sizeof(__le32) - \ + DEF_INLINE_RESERVED_SIZE - \ + MIN_INLINE_DENTRY_SIZE / sizeof(__le32)) + /* * On-disk structure of f2fs_xattr * We use inline xattrs space + 1 block for xattr. |