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authorChao Yu <yuchao0@huawei.com>2019-03-04 17:19:04 +0800
committerJaegeuk Kim <jaegeuk@kernel.org>2019-03-12 19:02:26 -0700
commitdd6c89b5f2b93ceced4111e7b69d4efd8c312713 (patch)
tree38e9e03aa5cd85dc7fcd0125a51097a3f7a44e8d /fs/f2fs/xattr.h
parent70db5b04cbe19e5ae7e85ada2d3e82bcfdf90352 (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.h6
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.