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authorDavid Howells <dhowells@redhat.com>2021-03-02 10:26:45 +0000
committerDavid Howells <dhowells@redhat.com>2021-03-15 17:01:18 +0000
commit64fcbb6158ecc684d84c64424830a9c37c77c5b9 (patch)
tree31d977f14f31189fcfdf5cde57b51a09aa281c05 /fs/afs
parenta38fd8748464831584a19438cbb3082b5a2dab15 (diff)
downloadlinux-64fcbb6158ecc684d84c64424830a9c37c77c5b9.tar.bz2
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
Diffstat (limited to 'fs/afs')
-rw-r--r--fs/afs/fs_operation.c7
-rw-r--r--fs/afs/xattr.c8
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 = {