diff options
| author | David Howells <dhowells@redhat.com> | 2021-03-02 10:26:45 +0000 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2021-03-15 17:01:18 +0000 |
| commit | 64fcbb6158ecc684d84c64424830a9c37c77c5b9 (patch) | |
| tree | 31d977f14f31189fcfdf5cde57b51a09aa281c05 | |
| parent | a38fd8748464831584a19438cbb3082b5a2dab15 (diff) | |
afs: Fix accessing YFS xattrs on a non-YFS server
If someone attempts to access YFS-related xattrs (e.g. afs.yfs.acl) on a
file on a non-YFS AFS server (such as OpenAFS), then the kernel will jump
to a NULL function pointer because the afs_fetch_acl_operation descriptor
doesn't point to a function for issuing an operation on a non-YFS
server[1].
Fix this by making afs_wait_for_operation() check that the issue_afs_rpc
method is set before jumping to it and setting -ENOTSUPP if not. This fix
also covers other potential operations that also only exist on YFS servers.
afs_xattr_get/set_yfs() then need to translate -ENOTSUPP to -ENODATA as the
former error is internal to the kernel.
The bug shows up as an oops like the following:
BUG: kernel NULL pointer dereference, address: 0000000000000000
[...]
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
[...]
Call Trace:
afs_wait_for_operation+0x83/0x1b0 [kafs]
afs_xattr_get_yfs+0xe6/0x270 [kafs]
__vfs_getxattr+0x59/0x80
vfs_getxattr+0x11c/0x140
getxattr+0x181/0x250
? __check_object_size+0x13f/0x150
? __fput+0x16d/0x250
__x64_sys_fgetxattr+0x64/0xb0
do_syscall_64+0x49/0xc0
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7fb120a9defe
This was triggered with "cp -a" which attempts to copy xattrs, including
afs ones, but is easier to reproduce with getfattr, e.g.:
getfattr -d -m ".*" /afs/openafs.org/
Fixes: e49c7b2f6de7 ("afs: Build an abstraction around an "operation" concept")
Reported-by: Gaja Sophie Peters <gaja.peters@math.uni-hamburg.de>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Gaja Sophie Peters <gaja.peters@math.uni-hamburg.de>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Reviewed-by: Jeffrey Altman <jaltman@auristor.com>
cc: linux-afs@lists.infradead.org
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003498.html [1]
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003566.html # v1
Link: http://lists.infradead.org/pipermail/linux-afs/2021-March/003572.html # v2
| -rw-r--r-- | fs/afs/fs_operation.c | 7 | ||||
| -rw-r--r-- | fs/afs/xattr.c | 8 |
2 files changed, 12 insertions, 3 deletions
diff --git a/fs/afs/fs_operation.c b/fs/afs/fs_operation.c index 97cab12b0a6c..71c58723763d 100644 --- a/fs/afs/fs_operation.c +++ b/fs/afs/fs_operation.c @@ -181,10 +181,13 @@ void afs_wait_for_operation(struct afs_operation *op) if (test_bit(AFS_SERVER_FL_IS_YFS, &op->server->flags) && op->ops->issue_yfs_rpc) op->ops->issue_yfs_rpc(op); - else + else if (op->ops->issue_afs_rpc) op->ops->issue_afs_rpc(op); + else + op->ac.error = -ENOTSUPP; - op->error = afs_wait_for_call_to_complete(op->call, &op->ac); + if (op->call) + op->error = afs_wait_for_call_to_complete(op->call, &op->ac); } switch (op->error) { diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c index c629caae5002..4934e325a14a 100644 --- a/fs/afs/xattr.c +++ b/fs/afs/xattr.c @@ -231,6 +231,8 @@ static int afs_xattr_get_yfs(const struct xattr_handler *handler, else ret = -ERANGE; } + } else if (ret == -ENOTSUPP) { + ret = -ENODATA; } error_yacl: @@ -256,6 +258,7 @@ static int afs_xattr_set_yfs(const struct xattr_handler *handler, { struct afs_operation *op; struct afs_vnode *vnode = AFS_FS_I(inode); + int ret; if (flags == XATTR_CREATE || strcmp(name, "acl") != 0) @@ -270,7 +273,10 @@ static int afs_xattr_set_yfs(const struct xattr_handler *handler, return afs_put_operation(op); op->ops = &yfs_store_opaque_acl2_operation; - return afs_do_sync_operation(op); + ret = afs_do_sync_operation(op); + if (ret == -ENOTSUPP) + ret = -ENODATA; + return ret; } static const struct xattr_handler afs_xattr_yfs_handler = { |