diff options
| author | Alexandra Winter <wintera@linux.ibm.com> | 2024-07-29 14:28:16 +0200 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2024-07-30 15:01:50 +0200 |
| commit | f558120cd709682b739207b48cf7479fd9568431 (patch) | |
| tree | 6c5d9a491a79946c4fd64975207c94c55631f75d /net/iucv | |
| parent | 2fe5273f149cc882c371f9954b5fdbd1bd8c9b5c (diff) | |
net/iucv: fix use after free in iucv_sock_close()
iucv_sever_path() is called from process context and from bh context.
iucv->path is used as indicator whether somebody else is taking care of
severing the path (or it is already removed / never existed).
This needs to be done with atomic compare and swap, otherwise there is a
small window where iucv_sock_close() will try to work with a path that has
already been severed and freed by iucv_callback_connrej() called by
iucv_tasklet_fn().
Example:
[452744.123844] Call Trace:
[452744.123845] ([<0000001e87f03880>] 0x1e87f03880)
[452744.123966] [<00000000d593001e>] iucv_path_sever+0x96/0x138
[452744.124330] [<000003ff801ddbca>] iucv_sever_path+0xc2/0xd0 [af_iucv]
[452744.124336] [<000003ff801e01b6>] iucv_sock_close+0xa6/0x310 [af_iucv]
[452744.124341] [<000003ff801e08cc>] iucv_sock_release+0x3c/0xd0 [af_iucv]
[452744.124345] [<00000000d574794e>] __sock_release+0x5e/0xe8
[452744.124815] [<00000000d5747a0c>] sock_close+0x34/0x48
[452744.124820] [<00000000d5421642>] __fput+0xba/0x268
[452744.124826] [<00000000d51b382c>] task_work_run+0xbc/0xf0
[452744.124832] [<00000000d5145710>] do_notify_resume+0x88/0x90
[452744.124841] [<00000000d5978096>] system_call+0xe2/0x2c8
[452744.125319] Last Breaking-Event-Address:
[452744.125321] [<00000000d5930018>] iucv_path_sever+0x90/0x138
[452744.125324]
[452744.125325] Kernel panic - not syncing: Fatal exception in interrupt
Note that bh_lock_sock() is not serializing the tasklet context against
process context, because the check for sock_owned_by_user() and
corresponding handling is missing.
Ideas for a future clean-up patch:
A) Correct usage of bh_lock_sock() in tasklet context, as described in
Link: https://lore.kernel.org/netdev/1280155406.2899.407.camel@edumazet-laptop/
Re-enqueue, if needed. This may require adding return values to the
tasklet functions and thus changes to all users of iucv.
B) Change iucv tasklet into worker and use only lock_sock() in af_iucv.
Fixes: 7d316b945352 ("af_iucv: remove IUCV-pathes completely")
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Alexandra Winter <wintera@linux.ibm.com>
Link: https://patch.msgid.link/20240729122818.947756-1-wintera@linux.ibm.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/iucv')
| -rw-r--r-- | net/iucv/af_iucv.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c index c3b0b610b0aa..c00323fa9eb6 100644 --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -335,8 +335,8 @@ static void iucv_sever_path(struct sock *sk, int with_user_data) struct iucv_sock *iucv = iucv_sk(sk); struct iucv_path *path = iucv->path; - if (iucv->path) { - iucv->path = NULL; + /* Whoever resets the path pointer, must sever and free it. */ + if (xchg(&iucv->path, NULL)) { if (with_user_data) { low_nmcpy(user_data, iucv->src_name); high_nmcpy(user_data, iucv->dst_name); |