f2fs: fix to avoid accessing xattr across the boundary
When we traverse xattr entries via __find_xattr(), if the raw filesystem content is faked or any hardware failure occurs, out-of-bound error can be detected by KASAN. Fix the issue by introducing boundary check. [ 38.402878] c7 1827 BUG: KASAN: slab-out-of-bounds in f2fs_getxattr+0x518/0x68c [ 38.402891] c7 1827 Read of size 4 at addr ffffffc0b6fb35dc by task [ 38.402935] c7 1827 Call trace: [ 38.402952] c7 1827 [<ffffff900809003c>] dump_backtrace+0x0/0x6bc [ 38.402966] c7 1827 [<ffffff9008090030>] show_stack+0x20/0x2c [ 38.402981] c7 1827 [<ffffff900871ab10>] dump_stack+0xfc/0x140 [ 38.402995] c7 1827 [<ffffff9008325c40>] print_address_description+0x80/0x2d8 [ 38.403009] c7 1827 [<ffffff900832629c>] kasan_report_error+0x198/0x1fc [ 38.403022] c7 1827 [<ffffff9008326104>] kasan_report_error+0x0/0x1fc [ 38.403037] c7 1827 [<ffffff9008325000>] __asan_load4+0x1b0/0x1b8 [ 38.403051] c7 1827 [<ffffff90085fcc44>] f2fs_getxattr+0x518/0x68c [ 38.403066] c7 1827 [<ffffff90085fc508>] f2fs_xattr_generic_get+0xb0/0xd0 [ 38.403080] c7 1827 [<ffffff9008395708>] __vfs_getxattr+0x1f4/0x1fc [ 38.403096] c7 1827 [<ffffff9008621bd0>] inode_doinit_with_dentry+0x360/0x938 [ 38.403109] c7 1827 [<ffffff900862d6cc>] selinux_d_instantiate+0x2c/0x38 [ 38.403123] c7 1827 [<ffffff900861b018>] security_d_instantiate+0x68/0x98 [ 38.403136] c7 1827 [<ffffff9008377db8>] d_splice_alias+0x58/0x348 [ 38.403149] c7 1827 [<ffffff900858d16c>] f2fs_lookup+0x608/0x774 [ 38.403163] c7 1827 [<ffffff900835eacc>] lookup_slow+0x1e0/0x2cc [ 38.403177] c7 1827 [<ffffff9008367fe0>] walk_component+0x160/0x520 [ 38.403190] c7 1827 [<ffffff9008369ef4>] path_lookupat+0x110/0x2b4 [ 38.403203] c7 1827 [<ffffff900835dd38>] filename_lookup+0x1d8/0x3a8 [ 38.403216] c7 1827 [<ffffff900835eeb0>] user_path_at_empty+0x54/0x68 [ 38.403229] c7 1827 [<ffffff9008395f44>] SyS_getxattr+0xb4/0x18c [ 38.403241] c7 1827 [<ffffff9008084200>] el0_svc_naked+0x34/0x38 Signed-off-by: Randall Huang <huangrandall@google.com> [Jaegeuk Kim: Fix wrong ending boundary] Reviewed-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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c9c8ed50d9
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2777e65437
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@ -202,12 +202,17 @@ static inline const struct xattr_handler *f2fs_xattr_handler(int index)
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return handler;
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}
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static struct f2fs_xattr_entry *__find_xattr(void *base_addr, int index,
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size_t len, const char *name)
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static struct f2fs_xattr_entry *__find_xattr(void *base_addr,
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void *last_base_addr, int index,
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size_t len, const char *name)
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{
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struct f2fs_xattr_entry *entry;
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list_for_each_xattr(entry, base_addr) {
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if ((void *)(entry) + sizeof(__u32) > last_base_addr ||
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(void *)XATTR_NEXT_ENTRY(entry) > last_base_addr)
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return NULL;
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if (entry->e_name_index != index)
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continue;
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if (entry->e_name_len != len)
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@ -297,20 +302,22 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage,
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const char *name, struct f2fs_xattr_entry **xe,
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void **base_addr, int *base_size)
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{
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void *cur_addr, *txattr_addr, *last_addr = NULL;
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void *cur_addr, *txattr_addr, *last_txattr_addr;
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void *last_addr = NULL;
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nid_t xnid = F2FS_I(inode)->i_xattr_nid;
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unsigned int size = xnid ? VALID_XATTR_BLOCK_SIZE : 0;
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unsigned int inline_size = inline_xattr_size(inode);
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int err = 0;
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if (!size && !inline_size)
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if (!xnid && !inline_size)
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return -ENODATA;
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*base_size = inline_size + size + XATTR_PADDING_SIZE;
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*base_size = XATTR_SIZE(xnid, inode) + XATTR_PADDING_SIZE;
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txattr_addr = f2fs_kzalloc(F2FS_I_SB(inode), *base_size, GFP_NOFS);
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if (!txattr_addr)
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return -ENOMEM;
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last_txattr_addr = (void *)txattr_addr + XATTR_SIZE(xnid, inode);
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/* read from inline xattr */
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if (inline_size) {
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err = read_inline_xattr(inode, ipage, txattr_addr);
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@ -337,7 +344,11 @@ static int lookup_all_xattrs(struct inode *inode, struct page *ipage,
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else
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cur_addr = txattr_addr;
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*xe = __find_xattr(cur_addr, index, len, name);
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*xe = __find_xattr(cur_addr, last_txattr_addr, index, len, name);
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if (!*xe) {
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err = -EFAULT;
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goto out;
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}
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check:
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if (IS_XATTR_LAST_ENTRY(*xe)) {
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err = -ENODATA;
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@ -581,7 +592,8 @@ static int __f2fs_setxattr(struct inode *inode, int index,
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struct page *ipage, int flags)
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{
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struct f2fs_xattr_entry *here, *last;
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void *base_addr;
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void *base_addr, *last_base_addr;
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nid_t xnid = F2FS_I(inode)->i_xattr_nid;
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int found, newsize;
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size_t len;
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__u32 new_hsize;
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@ -605,8 +617,14 @@ static int __f2fs_setxattr(struct inode *inode, int index,
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if (error)
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return error;
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last_base_addr = (void *)base_addr + XATTR_SIZE(xnid, inode);
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/* find entry with wanted name. */
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here = __find_xattr(base_addr, index, len, name);
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here = __find_xattr(base_addr, last_base_addr, index, len, name);
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if (!here) {
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error = -EFAULT;
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goto exit;
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}
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found = IS_XATTR_LAST_ENTRY(here) ? 0 : 1;
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@ -71,6 +71,8 @@ struct f2fs_xattr_entry {
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entry = XATTR_NEXT_ENTRY(entry))
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#define VALID_XATTR_BLOCK_SIZE (PAGE_SIZE - sizeof(struct node_footer))
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#define XATTR_PADDING_SIZE (sizeof(__u32))
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#define XATTR_SIZE(x,i) (((x) ? VALID_XATTR_BLOCK_SIZE : 0) + \
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(inline_xattr_size(i)))
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#define MIN_OFFSET(i) XATTR_ALIGN(inline_xattr_size(i) + \
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VALID_XATTR_BLOCK_SIZE)
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