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| author | David Howells <dhowells@redhat.com> | 2017-03-16 17:27:46 +0100 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2017-03-16 17:27:46 +0100 |
| commit | 29f069853287dcb46eaf45a50dbf1232c1444ac6 (patch) | |
| tree | 1ac522ed0e804b9bb0fdbdbe338217f997e5c1f0 /fs/afs | |
| parent | afs: Prevent callback expiry timer overflow (diff) | |
| download | linux-29f069853287dcb46eaf45a50dbf1232c1444ac6.tar.xz linux-29f069853287dcb46eaf45a50dbf1232c1444ac6.zip | |
afs: Fix AFS read bug
Fix a bug in AFS read whereby the request page afs_read::index isn't
incremented after calling ->page_done() if ->remain reaches 0, indicating
that the data read is complete.
Without this a NULL pointer exception happens when ->page_done() is called
twice for the last page because the page clearing loop will call it also
and afs_readpages_page_done() clears the current entry in the page list.
BUG: unable to handle kernel NULL pointer dereference at (null)
IP: afs_readpages_page_done+0x21/0xa4 [kafs]
PGD 0
Oops: 0002 [#1] SMP
Modules linked in: kafs(E)
CPU: 2 PID: 3002 Comm: md5sum Tainted: G E 4.10.0-fscache #485
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
task: ffff8804017d86c0 task.stack: ffff8803fc1d8000
RIP: 0010:afs_readpages_page_done+0x21/0xa4 [kafs]
RSP: 0018:ffff8803fc1db978 EFLAGS: 00010282
RAX: ffff880405d39af8 RBX: 0000000000000000 RCX: ffff880407d83ed4
RDX: 0000000000000000 RSI: ffff880405d39a00 RDI: ffff880405c6f400
RBP: ffff8803fc1db988 R08: 0000000000000000 R09: 0000000000000001
R10: ffff8803fc1db820 R11: ffff88040cf56000 R12: ffff8804088f1780
R13: ffff8804017d86c0 R14: ffff8804088f1780 R15: 0000000000003840
FS: 00007f8154469700(0000) GS:ffff88041fb00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000004016ec000 CR4: 00000000001406e0
Call Trace:
afs_deliver_fs_fetch_data+0x5b9/0x60e [kafs]
? afs_make_call+0x316/0x4e8 [kafs]
? afs_make_call+0x359/0x4e8 [kafs]
afs_deliver_to_call+0x173/0x2e8 [kafs]
? afs_make_call+0x316/0x4e8 [kafs]
afs_make_call+0x37a/0x4e8 [kafs]
? wake_up_q+0x4f/0x4f
? __init_waitqueue_head+0x36/0x49
afs_fs_fetch_data+0x21c/0x227 [kafs]
? afs_fs_fetch_data+0x21c/0x227 [kafs]
afs_vnode_fetch_data+0xf3/0x1d2 [kafs]
afs_readpages+0x314/0x3fd [kafs]
__do_page_cache_readahead+0x208/0x2c5
ondemand_readahead+0x3a2/0x3b7
? ondemand_readahead+0x3a2/0x3b7
page_cache_async_readahead+0x5e/0x67
generic_file_read_iter+0x23b/0x70c
? __inode_security_revalidate+0x2f/0x62
__vfs_read+0xc4/0xe8
vfs_read+0xd1/0x15a
SyS_read+0x4c/0x89
do_syscall_64+0x80/0x191
entry_SYSCALL64_slow_path+0x25/0x25
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.dionne@auristor.com>
Diffstat (limited to 'fs/afs')
| -rw-r--r-- | fs/afs/fsclient.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/afs/fsclient.c b/fs/afs/fsclient.c index c05452a09398..4314f9e63a2c 100644 --- a/fs/afs/fsclient.c +++ b/fs/afs/fsclient.c @@ -390,9 +390,9 @@ static int afs_deliver_fs_fetch_data(struct afs_call *call) if (call->offset == PAGE_SIZE) { if (req->page_done) req->page_done(call, req); + req->index++; if (req->remain > 0) { call->offset = 0; - req->index++; if (req->index >= req->nr_pages) { call->unmarshall = 4; goto begin_discard; |