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64fcbb6158
linux/fs/afs
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David Howells 64fcbb6158 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: e49c7b2f6d ("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
2021-03-15 17:01:18 +00:00
..
addr_list.c afs: Use kfree_rcu() instead of casting kfree() to rcu_callback_t 2020-03-13 10:47:33 -07:00
afs_cm.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
afs_fs.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
afs_vl.h afs: Implement client support for the YFSVL.GetCellName RPC op 2020-06-04 15:37:57 +01:00
afs.h afs: Implement client support for the YFSVL.GetCellName RPC op 2020-06-04 15:37:57 +01:00
cache.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
callback.c afs: Fix the by-UUID server tree to allow servers with the same UUID 2020-06-04 15:37:57 +01:00
cell.c afs: Fix tracing deref-before-check 2020-10-27 22:05:56 +00:00
cmservice.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
dir_edit.c afs: Fix directory entry size calculation 2021-01-04 12:25:19 +00:00
dir_silly.c afs: Fix silly rename 2020-06-16 22:00:28 +01:00
dir.c fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
dynroot.c afs: Add tracing for cell refcount and active user count 2020-10-16 14:39:21 +01:00
file.c afs: Fix afs_invalidatepage to adjust the dirty region 2020-10-29 13:53:04 +00:00
flock.c afs: Remove erroneous fallthough annotation 2020-08-27 14:33:01 -05:00
fs_operation.c afs: Fix accessing YFS xattrs on a non-YFS server 2021-03-15 17:01:18 +00:00
fs_probe.c rxrpc: Make rxrpc_kernel_get_srtt() indicate validity 2020-08-20 18:21:28 +01:00
fsclient.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
inode.c fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
internal.h fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
Kconfig docs: filesystems: fix renamed references 2020-04-20 15:45:22 -06:00
main.c rxrpc: Fix deadlock around release of dst cached on udp tunnel 2021-01-29 21:38:11 -08:00
Makefile afs: Detect cell aliases 1 - Cells with root volumes 2020-06-04 15:37:57 +01:00
misc.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
mntpt.c afs: Add tracing for cell refcount and active user count 2020-10-16 14:39:21 +01:00
proc.c afs: Add tracing for cell refcount and active user count 2020-10-16 14:39:21 +01:00
protocol_uae.h afs: Add support for the UAE error table 2019-06-28 18:37:53 +01:00
protocol_yfs.h afs: Implement client support for the YFSVL.GetCellName RPC op 2020-06-04 15:37:57 +01:00
rotate.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
rxrpc.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
security.c fs: make helpers idmap mount aware 2021-01-24 14:27:20 +01:00
server_list.c afs: Reorganise volume and server trees to be rooted on the cell 2020-06-04 15:37:57 +01:00
server.c afs: Don't assert on unpurgeable server records 2020-10-16 14:39:34 +01:00
super.c afs: Fix memory leak when mounting with multiple source parameters 2020-12-08 15:59:25 -08:00
vl_alias.c afs: Add tracing for cell refcount and active user count 2020-10-16 14:39:21 +01:00
vl_list.c afs: Don't use VL probe running state to make decisions outside probe code 2020-08-20 18:21:28 +01:00
vl_probe.c afs: Don't use VL probe running state to make decisions outside probe code 2020-08-20 18:21:28 +01:00
vl_rotate.c afs: Add tracing for cell refcount and active user count 2020-10-16 14:39:21 +01:00
vlclient.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
volume.c afs: Add tracing for cell refcount and active user count 2020-10-16 14:39:21 +01:00
write.c afs: Fix afs_write_end() when called with copied == 0 [ver #3] 2020-11-14 11:51:18 -08:00
xattr.c afs: Fix accessing YFS xattrs on a non-YFS server 2021-03-15 17:01:18 +00:00
xdr_fs.h afs: Fix directory entry size calculation 2021-01-04 12:25:19 +00:00
yfsclient.c afs: Fix warning due to unadvanced marshalling pointer 2020-11-03 09:53:40 -08:00