From mboxrd@z Thu Jan 1 00:00:00 1970 From: gregkh@linuxfoundation.org (gregkh@linuxfoundation.org) Date: Tue, 12 Mar 2019 05:57:36 -0700 Subject: Patch "staging: erofs: fix race of initializing xattrs of a inode at the same time" has been added to the 4.19-stable tree In-Reply-To: <20190311060858.28654-4-gaoxiang25@huawei.com> Message-ID: <1552395456224210@kroah.com> This is a note to let you know that I've just added the patch titled staging: erofs: fix race of initializing xattrs of a inode at the same time to the 4.19-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: staging-erofs-fix-race-of-initializing-xattrs-of-a-inode-at-the-same-time.patch and it can be found in the queue-4.19 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From foo at baz Tue Mar 12 05:46:41 PDT 2019 From: Gao Xiang Date: Mon, 11 Mar 2019 14:08:57 +0800 Subject: staging: erofs: fix race of initializing xattrs of a inode at the same time To: Cc: Greg Kroah-Hartman , LKML , , Chao Yu , Chao Yu , Miao Xie , Fang Wei , Gao Xiang Message-ID: <20190311060858.28654-4-gaoxiang25 at huawei.com> From: Gao Xiang commit 62dc45979f3f8cb0ea67302a93bff686f0c46c5a upstream. In real scenario, there could be several threads accessing xattrs of the same xattr-uninitialized inode, and init_inode_xattrs() almost at the same time. That's actually an unexpected behavior, this patch closes the race. Fixes: b17500a0fdba ("staging: erofs: introduce xattr & acl support") Cc: # 4.19+ Reviewed-by: Chao Yu Signed-off-by: Gao Xiang Signed-off-by: Greg Kroah-Hartman --- drivers/staging/erofs/internal.h | 11 +++++++--- drivers/staging/erofs/xattr.c | 41 +++++++++++++++++++++++++++------------ 2 files changed, 37 insertions(+), 15 deletions(-) --- a/drivers/staging/erofs/internal.h +++ b/drivers/staging/erofs/internal.h @@ -327,12 +327,17 @@ static inline erofs_off_t iloc(struct er return blknr_to_addr(sbi->meta_blkaddr) + (nid << sbi->islotbits); } -#define inode_set_inited_xattr(inode) (EROFS_V(inode)->flags |= 1) -#define inode_has_inited_xattr(inode) (EROFS_V(inode)->flags & 1) +/* atomic flag definitions */ +#define EROFS_V_EA_INITED_BIT 0 + +/* bitlock definitions (arranged in reverse order) */ +#define EROFS_V_BL_XATTR_BIT (BITS_PER_LONG - 1) struct erofs_vnode { erofs_nid_t nid; - unsigned int flags; + + /* atomic flags (including bitlocks) */ + unsigned long flags; unsigned char data_mapping_mode; /* inline size in bytes */ --- a/drivers/staging/erofs/xattr.c +++ b/drivers/staging/erofs/xattr.c @@ -44,17 +44,24 @@ static inline void xattr_iter_end_final( static int init_inode_xattrs(struct inode *inode) { + struct erofs_vnode *const vi = EROFS_V(inode); struct xattr_iter it; unsigned i; struct erofs_xattr_ibody_header *ih; struct erofs_sb_info *sbi; - struct erofs_vnode *vi; bool atomic_map; + int ret = 0; - if (likely(inode_has_inited_xattr(inode))) + /* the most case is that xattrs of this inode are initialized. */ + if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags)) return 0; - vi = EROFS_V(inode); + if (wait_on_bit_lock(&vi->flags, EROFS_V_BL_XATTR_BIT, TASK_KILLABLE)) + return -ERESTARTSYS; + + /* someone has initialized xattrs for us? */ + if (test_bit(EROFS_V_EA_INITED_BIT, &vi->flags)) + goto out_unlock; /* * bypass all xattr operations if ->xattr_isize is not greater than @@ -67,13 +74,16 @@ static int init_inode_xattrs(struct inod 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; + ret = -ENOTSUPP; + goto out_unlock; } 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 */ + ret = -EIO; + goto out_unlock; /* xattr ondisk layout error */ } - return -ENOATTR; + ret = -ENOATTR; + goto out_unlock; } sbi = EROFS_I_SB(inode); @@ -81,8 +91,10 @@ static int init_inode_xattrs(struct inod it.ofs = erofs_blkoff(iloc(sbi, vi->nid) + vi->inode_isize); it.page = erofs_get_inline_page(inode, it.blkaddr); - if (IS_ERR(it.page)) - return PTR_ERR(it.page); + if (IS_ERR(it.page)) { + ret = PTR_ERR(it.page); + goto out_unlock; + } /* read in shared xattr array (non-atomic, see kmalloc below) */ it.kaddr = kmap(it.page); @@ -95,7 +107,8 @@ static int init_inode_xattrs(struct inod sizeof(uint), GFP_KERNEL); if (!vi->xattr_shared_xattrs) { xattr_iter_end(&it, atomic_map); - return -ENOMEM; + ret = -ENOMEM; + goto out_unlock; } /* let's skip ibody header */ @@ -112,7 +125,8 @@ static int init_inode_xattrs(struct inod if (IS_ERR(it.page)) { kfree(vi->xattr_shared_xattrs); vi->xattr_shared_xattrs = NULL; - return PTR_ERR(it.page); + ret = PTR_ERR(it.page); + goto out_unlock; } it.kaddr = kmap_atomic(it.page); @@ -125,8 +139,11 @@ static int init_inode_xattrs(struct inod } xattr_iter_end(&it, atomic_map); - inode_set_inited_xattr(inode); - return 0; + set_bit(EROFS_V_EA_INITED_BIT, &vi->flags); + +out_unlock: + clear_and_wake_up_bit(EROFS_V_BL_XATTR_BIT, &vi->flags); + return ret; } struct xattr_iter_handlers { Patches currently in stable-queue which might be from gaoxiang25 at huawei.com are queue-4.19/staging-erofs-fix-fast-symlink-w-o-xattr-when-fs-xattr-is-on.patch queue-4.19/staging-erofs-fix-race-of-initializing-xattrs-of-a-inode-at-the-same-time.patch queue-4.19/staging-erofs-add-error-handling-for-xattr-submodule.patch queue-4.19/staging-erofs-keep-corrupted-fs-from-crashing-kernel-in-erofs_namei.patch queue-4.19/staging-erofs-fix-memleak-of-inode-s-shared-xattr-array.patch