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Commit 9dc84155 authored by Gao Xiang's avatar Gao Xiang Committed by Greg Kroah-Hartman
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staging: erofs: fix fast symlink w/o xattr when fs xattr is on 



commit 7077fffcb0b0b65dc75e341306aeef4d0e7f2ec6 upstream.

Currently, this will hit a BUG_ON for these symlinks as follows:

- kernel message
------------[ cut here ]------------
kernel BUG at drivers/staging/erofs/xattr.c:59!
SMP PTI
CPU: 1 PID: 1170 Comm: getllxattr Not tainted 4.20.0-rc6+ #92
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-2.fc27 04/01/2014
RIP: 0010:init_inode_xattrs+0x22b/0x270
Code: 48 0f 45 ea f0 ff 4d 34 74 0d 41 83 4c 24 e0 01 31 c0 e9 00 fe ff ff 48 89 ef e8 e0 31 9e ff eb e9 89 e8 e9 ef fd ff ff 0f 0$
 <0f> 0b 48 89 ef e8 fb f6 9c ff 48 8b 45 08 a8 01 75 24 f0 ff 4d 34
RSP: 0018:ffffa03ac026bdf8 EFLAGS: 00010246
------------[ cut here ]------------
...
Call Trace:
 erofs_listxattr+0x30/0x2c0
 ? selinux_inode_listxattr+0x5a/0x80
 ? kmem_cache_alloc+0x33/0x170
 ? security_inode_listxattr+0x27/0x40
 listxattr+0xaf/0xc0
 path_listxattr+0x5a/0xa0
 do_syscall_64+0x43/0xf0
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
...
---[ end trace 3c24b49408dc0c72 ]---

Fix it by checking ->xattr_isize in init_inode_xattrs(),
and it also fixes improper return value -ENOTSUPP
(it should be -ENODATA if xattr is enabled) for those inodes.

Fixes: b17500a0 ("staging: erofs: introduce xattr & acl support")
Cc: <stable@vger.kernel.org> # 4.19+
Reported-by: default avatarLi Guifu <bluce.liguifu@huawei.com>
Tested-by: default avatarLi Guifu <bluce.liguifu@huawei.com>
Reviewed-by: default avatarChao Yu <yuchao0@huawei.com>
Signed-off-by: default avatarGao Xiang <gaoxiang25@huawei.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent f581642c

drivers/staging/erofs/inode.c

+4 −4
Original line number Diff line number Diff line
@@ -184,16 +184,16 @@ static int fill_inode(struct inode *inode, int isdir) 
		/* setup the new inode */

		if (S_ISREG(inode->i_mode)) {

#ifdef CONFIG_EROFS_FS_XATTR

			if (vi->xattr_isize)

			inode->i_op = &erofs_generic_xattr_iops;

#endif

			inode->i_fop = &generic_ro_fops;

		} else if (S_ISDIR(inode->i_mode)) {

			inode->i_op =

#ifdef CONFIG_EROFS_FS_XATTR

				vi->xattr_isize ? &erofs_dir_xattr_iops :

#endif

				&erofs_dir_xattr_iops;

#else

				&erofs_dir_iops;

#endif

			inode->i_fop = &erofs_dir_fops;

		} else if (S_ISLNK(inode->i_mode)) {

			/* by default, page_get_link is used for symlink */

drivers/staging/erofs/xattr.c

+20 −5
Original line number Diff line number Diff line
@@ -55,7 +55,26 @@ static int init_inode_xattrs(struct inode *inode) 
		return 0;



	vi = EROFS_V(inode);

	BUG_ON(!vi->xattr_isize);



	/*

	 * bypass all xattr operations if ->xattr_isize is not greater than

	 * sizeof(struct erofs_xattr_ibody_header), in detail:

	 * 1) it is not enough to contain erofs_xattr_ibody_header then

	 *    ->xattr_isize should be 0 (it means no xattr);

	 * 2) it is just to contain erofs_xattr_ibody_header, which is on-disk

	 *    undefined right now (maybe use later with some new sb feature).

	 */

	if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {

		errln("xattr_isize %d of nid %llu is not supported yet",

		      vi->xattr_isize, vi->nid);

		return -ENOTSUPP;

	} else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {

		if (unlikely(vi->xattr_isize)) {

			DBG_BUGON(1);

			return -EIO;	/* xattr ondisk layout error */

		}

		return -ENOATTR;

	}



	sbi = EROFS_I_SB(inode);

	it.blkaddr = erofs_blknr(iloc(sbi, vi->nid) + vi->inode_isize);
@@ -414,7 +433,6 @@ static int erofs_xattr_generic_get(const struct xattr_handler *handler, 
		struct dentry *unused, struct inode *inode,

		const char *name, void *buffer, size_t size)

{

	struct erofs_vnode *const vi = EROFS_V(inode);

	struct erofs_sb_info *const sbi = EROFS_I_SB(inode);



	switch (handler->flags) {
@@ -432,9 +450,6 @@ static int erofs_xattr_generic_get(const struct xattr_handler *handler, 
		return -EINVAL;

	}



	if (!vi->xattr_isize)

		return -ENOATTR;



	return erofs_getxattr(inode, handler->flags, name, buffer, size);

}