AFS: Stop readlink() on AFS crashing due to NULL 'file' ptr
kAFS crashes when asked to read a symbolic link because page_getlink()
passes a NULL file pointer to read_mapping_page(), but afs_readpage()
expects a file pointer from which to extract a key.
Modify afs_readpage() to request the appropriate key from the calling
process's keyrings if a file struct is not supplied with one attached.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/afs/file.c b/fs/afs/file.c
index 0149dab..681c2a7 100644
--- a/fs/afs/file.c
+++ b/fs/afs/file.c
@@ -134,9 +134,16 @@
inode = page->mapping->host;
- ASSERT(file != NULL);
- key = file->private_data;
- ASSERT(key != NULL);
+ if (file) {
+ key = file->private_data;
+ ASSERT(key != NULL);
+ } else {
+ key = afs_request_key(AFS_FS_S(inode->i_sb)->volume->cell);
+ if (IS_ERR(key)) {
+ ret = PTR_ERR(key);
+ goto error_nokey;
+ }
+ }
_enter("{%x},{%lu},{%lu}", key_serial(key), inode->i_ino, page->index);
@@ -207,12 +214,17 @@
unlock_page(page);
}
+ if (!file)
+ key_put(key);
_leave(" = 0");
return 0;
error:
SetPageError(page);
unlock_page(page);
+ if (!file)
+ key_put(key);
+error_nokey:
_leave(" = %d", ret);
return ret;
}
