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Subject[PATCH 4.9.y] ubifs: Massage assert in ubifs_xattr_set() wrt. init_xattrs
Date
From: Xiaolei Li <xiaolei.li@mediatek.com>

This is a conceptual cherry-pick of commit
d8db5b1ca9d4c57e49893d0f78e6d5ce81450cc8 upstream.

The inode is not locked in init_xattrs when creating a new inode.

Without this patch, there will occurs assert when booting or creating
a new file, if the kernel config CONFIG_SECURITY_SMACK is enabled.

Log likes:

UBIFS assert failed in ubifs_xattr_set at 298 (pid 1156)
CPU: 1 PID: 1156 Comm: ldconfig Tainted: G S 4.12.0-rc1-207440-g1e70b02 #2
Hardware name: MediaTek MT2712 evaluation board (DT)
Call trace:
[<ffff000008088538>] dump_backtrace+0x0/0x238
[<ffff000008088834>] show_stack+0x14/0x20
[<ffff0000083d98d4>] dump_stack+0x9c/0xc0
[<ffff00000835d524>] ubifs_xattr_set+0x374/0x5e0
[<ffff00000835d7ec>] init_xattrs+0x5c/0xb8
[<ffff000008385788>] security_inode_init_security+0x110/0x190
[<ffff00000835e058>] ubifs_init_security+0x30/0x68
[<ffff00000833ada0>] ubifs_mkdir+0x100/0x200
[<ffff00000820669c>] vfs_mkdir+0x11c/0x1b8
[<ffff00000820b73c>] SyS_mkdirat+0x74/0xd0
[<ffff000008082f8c>] __sys_trace_return+0x0/0x4

Signed-off-by: Xiaolei Li <xiaolei.li@mediatek.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Cc: stable@vger.kernel.org
(julia: massaged to apply to 4.9.y, which doesn't contain fscrypto support)
Signed-off-by: Julia Cartwright <julia@ni.com>
---
Hey all-

We reproduced the issue fixed upstream by Xiaolei Li's commit in 4.9.y,
with the very similar backtrace:

UBIFS assert failed in __ubifs_setxattr at 282 (pid 1362)
CPU: 1 PID: 1362 Comm: sed Not tainted 4.9.47-rt37 #1
Backtrace:
(dump_backtrace) from (show_stack+0x20/0x24)
(show_stack) from (dump_stack+0x80/0xa0)
(dump_stack) from (__ubifs_setxattr+0x84/0x634)
(__ubifs_setxattr) from (init_xattrs+0x70/0xac)
(init_xattrs) from (security_inode_init_security+0x100/0x144)
(security_inode_init_security) from (ubifs_init_security+0x38/0x6c)
(ubifs_init_security) from (ubifs_create+0xe8/0x1fc)
(ubifs_create) from (path_openat+0x97c/0x1090)
(path_openat) from (do_filp_open+0x48/0x94)
(do_filp_open) from (do_sys_open+0x134/0x1d8)
(do_sys_open) from (SyS_open+0x30/0x34)
(SyS_open) from (ret_fast_syscall+0x0/0x3c)

Please consider applying this to 4.9.y at the very least, it may apply
further back as well.

Thanks!
Julia

fs/ubifs/xattr.c | 12 ++++++++----
1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/ubifs/xattr.c b/fs/ubifs/xattr.c
index d9f9615bfd71..3979d767a0cb 100644
--- a/fs/ubifs/xattr.c
+++ b/fs/ubifs/xattr.c
@@ -270,7 +270,8 @@ static struct inode *iget_xattr(struct ubifs_info *c, ino_t inum)
}

static int __ubifs_setxattr(struct inode *host, const char *name,
- const void *value, size_t size, int flags)
+ const void *value, size_t size, int flags,
+ bool check_lock)
{
struct inode *inode;
struct ubifs_info *c = host->i_sb->s_fs_info;
@@ -279,7 +280,8 @@ static int __ubifs_setxattr(struct inode *host, const char *name,
union ubifs_key key;
int err;

- ubifs_assert(inode_is_locked(host));
+ if (check_lock)
+ ubifs_assert(inode_is_locked(host));

if (size > UBIFS_MAX_INO_DATA)
return -ERANGE;
@@ -548,7 +550,8 @@ static int init_xattrs(struct inode *inode, const struct xattr *xattr_array,
}
strcpy(name, XATTR_SECURITY_PREFIX);
strcpy(name + XATTR_SECURITY_PREFIX_LEN, xattr->name);
- err = __ubifs_setxattr(inode, name, xattr->value, xattr->value_len, 0);
+ err = __ubifs_setxattr(inode, name, xattr->value,
+ xattr->value_len, 0, false);
kfree(name);
if (err < 0)
break;
@@ -594,7 +597,8 @@ static int ubifs_xattr_set(const struct xattr_handler *handler,
name = xattr_full_name(handler, name);

if (value)
- return __ubifs_setxattr(inode, name, value, size, flags);
+ return __ubifs_setxattr(inode, name, value, size, flags,
+ true);
else
return __ubifs_removexattr(inode, name);
}
--
2.16.1
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