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: b17500a0fdba ("staging: erofs: introduce xattr & acl support") Cc: stable@vger.kernel.org # 4.19+ Reported-by: Li Guifu bluce.liguifu@huawei.com Tested-by: Li Guifu bluce.liguifu@huawei.com Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Gao Xiang gaoxiang25@huawei.com --- drivers/staging/erofs/inode.c | 8 ++++---- drivers/staging/erofs/xattr.c | 25 ++++++++++++++++++++----- 2 files changed, 24 insertions(+), 9 deletions(-)
diff --git a/drivers/staging/erofs/inode.c b/drivers/staging/erofs/inode.c index d7fbf5f4600f..f99954dbfdb5 100644 --- a/drivers/staging/erofs/inode.c +++ b/drivers/staging/erofs/inode.c @@ -185,16 +185,16 @@ 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; + 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 */ diff --git a/drivers/staging/erofs/xattr.c b/drivers/staging/erofs/xattr.c index 80dca6a4adbe..e30de2476fd0 100644 --- a/drivers/staging/erofs/xattr.c +++ b/drivers/staging/erofs/xattr.c @@ -56,7 +56,26 @@ 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; + }
sb = inode->i_sb; sbi = EROFS_SB(sb); @@ -422,7 +441,6 @@ 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) { @@ -440,9 +458,6 @@ 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); }