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 | |
| 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')
| -rw-r--r-- | fs/f2fs/inode.c | 15 | ||||
| -rw-r--r-- | fs/f2fs/super.c | 5 | ||||
| -rw-r--r-- | fs/f2fs/xattr.h | 6 |
3 files changed, 22 insertions, 4 deletions
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index bec52961630b..d44e6de70cb3 100644 --- a/fs/f2fs/inode.c +++ b/fs/f2fs/inode.c @@ -14,6 +14,7 @@ #include "f2fs.h" #include "node.h" #include "segment.h" +#include "xattr.h" #include <trace/events/f2fs.h> @@ -248,6 +249,20 @@ static bool sanity_check_inode(struct inode *inode, struct page *node_page) return false; } + if (f2fs_has_extra_attr(inode) && + f2fs_sb_has_flexible_inline_xattr(sbi) && + f2fs_has_inline_xattr(inode) && + (!fi->i_inline_xattr_size || + fi->i_inline_xattr_size > MAX_INLINE_XATTR_SIZE)) { + set_sbi_flag(sbi, SBI_NEED_FSCK); + f2fs_msg(sbi->sb, KERN_WARNING, + "%s: inode (ino=%lx) has corrupted " + "i_inline_xattr_size: %d, max: %zu", + __func__, inode->i_ino, fi->i_inline_xattr_size, + MAX_INLINE_XATTR_SIZE); + return false; + } + if (F2FS_I(inode)->extent_tree) { struct extent_info *ei = &F2FS_I(inode)->extent_tree->largest; diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 324938ec95f3..21750df930b3 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -838,10 +838,7 @@ static int parse_options(struct super_block *sb, char *options) } min_size = sizeof(struct f2fs_xattr_header) / sizeof(__le32); - max_size = DEF_ADDRS_PER_INODE - - F2FS_TOTAL_EXTRA_ATTR_SIZE / sizeof(__le32) - - DEF_INLINE_RESERVED_SIZE - - MIN_INLINE_DENTRY_SIZE / sizeof(__le32); + max_size = MAX_INLINE_XATTR_SIZE; if (F2FS_OPTION(sbi).inline_xattr_size < min_size || F2FS_OPTION(sbi).inline_xattr_size > max_size) { 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. |