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As Paul Bandha reported in bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=202709 When I run the poc on the mounted f2fs img I get a buffer overflow in read_inline_xattr due to there being no sanity check on the value of i_inline_xattr_size. I created the img by just modifying the value of i_inline_xattr_size in the inode: i_name [test1.txt] i_ext: fofs:0 blkaddr:0 len:0 i_extra_isize [0x 18 : 24] i_inline_xattr_size [0x ffff : 65535] i_addr[ofs] [0x 0 : 0] mkdir /mnt/f2fs mount ./f2fs1.img /mnt/f2fs gcc poc.c -o poc ./poc int main() { int y = syscall(SYS_listxattr, "/mnt/f2fs/test1.txt", NULL, 0); printf("ret %d", y); printf("errno: %d\n", errno); } BUG: KASAN: slab-out-of-bounds in read_inline_xattr+0x18f/0x260 Read of size 262140 at addr ffff88011035efd8 by task f2fs1poc/3263 CPU: 0 PID: 3263 Comm: f2fs1poc Not tainted 4.18.0-custom #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014 Call Trace: dump_stack+0x71/0xab print_address_description+0x83/0x250 kasan_report+0x213/0x350 memcpy+0x1f/0x50 read_inline_xattr+0x18f/0x260 read_all_xattrs+0xba/0x190 f2fs_listxattr+0x9d/0x3f0 listxattr+0xb2/0xd0 path_listxattr+0x93/0xe0 do_syscall_64+0x9d/0x220 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Let's add sanity check for inode.i_inline_xattr_size during f2fs_iget() to avoid this issue. Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
162 lines
4.8 KiB
C
162 lines
4.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/f2fs/xattr.h
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*
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* Copyright (c) 2012 Samsung Electronics Co., Ltd.
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* http://www.samsung.com/
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*
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* Portions of this code from linux/fs/ext2/xattr.h
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*
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* On-disk format of extended attributes for the ext2 filesystem.
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*
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* (C) 2001 Andreas Gruenbacher, <a.gruenbacher@computer.org>
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*/
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#ifndef __F2FS_XATTR_H__
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#define __F2FS_XATTR_H__
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#include <linux/init.h>
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#include <linux/xattr.h>
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/* Magic value in attribute blocks */
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#define F2FS_XATTR_MAGIC 0xF2F52011
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/* Maximum number of references to one attribute block */
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#define F2FS_XATTR_REFCOUNT_MAX 1024
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/* Name indexes */
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#define F2FS_SYSTEM_ADVISE_NAME "system.advise"
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#define F2FS_XATTR_INDEX_USER 1
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#define F2FS_XATTR_INDEX_POSIX_ACL_ACCESS 2
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#define F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT 3
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#define F2FS_XATTR_INDEX_TRUSTED 4
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#define F2FS_XATTR_INDEX_LUSTRE 5
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#define F2FS_XATTR_INDEX_SECURITY 6
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#define F2FS_XATTR_INDEX_ADVISE 7
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/* Should be same as EXT4_XATTR_INDEX_ENCRYPTION */
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#define F2FS_XATTR_INDEX_ENCRYPTION 9
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#define F2FS_XATTR_NAME_ENCRYPTION_CONTEXT "c"
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struct f2fs_xattr_header {
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__le32 h_magic; /* magic number for identification */
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__le32 h_refcount; /* reference count */
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__u32 h_reserved[4]; /* zero right now */
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};
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struct f2fs_xattr_entry {
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__u8 e_name_index;
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__u8 e_name_len;
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__le16 e_value_size; /* size of attribute value */
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char e_name[0]; /* attribute name */
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};
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#define XATTR_HDR(ptr) ((struct f2fs_xattr_header *)(ptr))
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#define XATTR_ENTRY(ptr) ((struct f2fs_xattr_entry *)(ptr))
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#define XATTR_FIRST_ENTRY(ptr) (XATTR_ENTRY(XATTR_HDR(ptr) + 1))
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#define XATTR_ROUND (3)
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#define XATTR_ALIGN(size) (((size) + XATTR_ROUND) & ~XATTR_ROUND)
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#define ENTRY_SIZE(entry) (XATTR_ALIGN(sizeof(struct f2fs_xattr_entry) + \
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(entry)->e_name_len + le16_to_cpu((entry)->e_value_size)))
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#define XATTR_NEXT_ENTRY(entry) ((struct f2fs_xattr_entry *)((char *)(entry) +\
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ENTRY_SIZE(entry)))
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#define IS_XATTR_LAST_ENTRY(entry) (*(__u32 *)(entry) == 0)
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#define list_for_each_xattr(entry, addr) \
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for (entry = XATTR_FIRST_ENTRY(addr);\
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!IS_XATTR_LAST_ENTRY(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 MIN_OFFSET(i) XATTR_ALIGN(inline_xattr_size(i) + \
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VALID_XATTR_BLOCK_SIZE)
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#define MAX_VALUE_LEN(i) (MIN_OFFSET(i) - \
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sizeof(struct f2fs_xattr_header) - \
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sizeof(struct f2fs_xattr_entry))
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#define MAX_INLINE_XATTR_SIZE \
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(DEF_ADDRS_PER_INODE - \
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F2FS_TOTAL_EXTRA_ATTR_SIZE / sizeof(__le32) - \
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DEF_INLINE_RESERVED_SIZE - \
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MIN_INLINE_DENTRY_SIZE / sizeof(__le32))
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/*
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* On-disk structure of f2fs_xattr
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* We use inline xattrs space + 1 block for xattr.
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*
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* +--------------------+
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* | f2fs_xattr_header |
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* | |
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* +--------------------+
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* | f2fs_xattr_entry |
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* | .e_name_index = 1 |
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* | .e_name_len = 3 |
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* | .e_value_size = 14 |
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* | .e_name = "foo" |
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* | "value_of_xattr" |<- value_offs = e_name + e_name_len
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* +--------------------+
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* | f2fs_xattr_entry |
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* | .e_name_index = 4 |
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* | .e_name = "bar" |
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* +--------------------+
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* | |
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* | Free |
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* | |
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* +--------------------+<- MIN_OFFSET
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* | node_footer |
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* | (nid, ino, offset) |
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* +--------------------+
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*
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**/
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#ifdef CONFIG_F2FS_FS_XATTR
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extern const struct xattr_handler f2fs_xattr_user_handler;
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extern const struct xattr_handler f2fs_xattr_trusted_handler;
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extern const struct xattr_handler f2fs_xattr_advise_handler;
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extern const struct xattr_handler f2fs_xattr_security_handler;
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extern const struct xattr_handler *f2fs_xattr_handlers[];
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extern int f2fs_setxattr(struct inode *, int, const char *,
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const void *, size_t, struct page *, int);
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extern int f2fs_getxattr(struct inode *, int, const char *, void *,
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size_t, struct page *);
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extern ssize_t f2fs_listxattr(struct dentry *, char *, size_t);
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#else
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#define f2fs_xattr_handlers NULL
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static inline int f2fs_setxattr(struct inode *inode, int index,
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const char *name, const void *value, size_t size,
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struct page *page, int flags)
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{
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return -EOPNOTSUPP;
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}
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static inline int f2fs_getxattr(struct inode *inode, int index,
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const char *name, void *buffer,
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size_t buffer_size, struct page *dpage)
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{
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return -EOPNOTSUPP;
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}
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static inline ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer,
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size_t buffer_size)
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{
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return -EOPNOTSUPP;
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}
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#endif
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#ifdef CONFIG_F2FS_FS_SECURITY
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extern int f2fs_init_security(struct inode *, struct inode *,
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const struct qstr *, struct page *);
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#else
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static inline int f2fs_init_security(struct inode *inode, struct inode *dir,
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const struct qstr *qstr, struct page *ipage)
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{
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return 0;
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}
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#endif
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#endif /* __F2FS_XATTR_H__ */
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