[PATCH v2] f2fs: fix to avoid memory leakage in f2fs_listxattr

[Randall Huang]

In f2fs_listxattr, there is no boundary check before
memcpy e_name to buffer.
If the e_name_len is corrupted,
unexpected memory contents may be returned to the buffer.

Signed-off-by: Randall Huang <huangrand...@google.com>
---
v2:
relocate sanity check
---
 fs/f2fs/xattr.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/xattr.c b/fs/f2fs/xattr.c
index 181900af2576..296b3189448a 100644
--- a/fs/f2fs/xattr.c
+++ b/fs/f2fs/xattr.c
@@ -539,8 +539,9 @@ int f2fs_getxattr(struct inode *inode, int index, const 
char *name,
 ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
 {
        struct inode *inode = d_inode(dentry);
+       nid_t xnid = F2FS_I(inode)->i_xattr_nid;
        struct f2fs_xattr_entry *entry;
-       void *base_addr;
+       void *base_addr, *last_base_addr;
        int error = 0;
        size_t rest = buffer_size;
 
@@ -550,6 +551,8 @@ ssize_t f2fs_listxattr(struct dentry *dentry, char *buffer, 
size_t buffer_size)
        if (error)
                return error;
 
+       last_base_addr = (void *)base_addr + XATTR_SIZE(xnid, inode);
+
        list_for_each_xattr(entry, base_addr) {
                const struct xattr_handler *handler =
                        f2fs_xattr_handler(entry->e_name_index);
@@ -557,6 +560,15 @@ ssize_t f2fs_listxattr(struct dentry *dentry, char 
*buffer, size_t buffer_size)
                size_t prefix_len;
                size_t size;
 
+               if ((void *)(entry) + sizeof(__u32) > last_base_addr ||
+                       (void *)XATTR_NEXT_ENTRY(entry) > last_base_addr) {
+                       f2fs_err(F2FS_I_SB(inode), "inode (%lu) has corrupted 
xattr",
+                                               inode->i_ino);
+                       set_sbi_flag(F2FS_I_SB(inode), SBI_NEED_FSCK);
+                       error = -EFSCORRUPTED;
+                       goto cleanup;
+               }
+
                if (!handler || (handler->list && !handler->list(dentry)))
                        continue;
 
-- 
2.23.0.866.gb869b98d4c-goog