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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>
This commit is contained in:
David Howells 2009-08-27 13:09:06 +01:00 committed by Linus Torvalds
parent 1e23502cc5
commit 9886e836a6
1 changed files with 15 additions and 3 deletions
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18
fs/afs/file.c
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@ -134,9 +134,16 @@ static int afs_readpage(struct file *file, struct page *page)
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 @@ static int afs_readpage(struct file *file, struct page *page)
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;
}