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When asked to use kqueue, AIO stores its internal state in the

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`kn_sdata' member of the newly registered knote. The problem is that
this member is overwritten by a call to kevent(2) with the EV_ADD flag,
targetted at the same kevent/knote. For instance, a userland application
may set the pointer to NULL, leading to a panic.

A testcase was provided by the submitter.

PR:	kern/118911
Submitted by:	MOROHOSHI Akihiko <moro@remus.dti.ne.jp>
MFC after:	1 day
This commit is contained in:
Jean-Sébastien Pédron 2008-01-24 17:10:19 +00:00
parent eee74fe05d
commit a8afa221cc
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=175642
2 changed files with 8 additions and 4 deletions
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10
sys/kern/vfs_aio.c
View File

@ -2251,6 +2251,7 @@ filt_aioattach(struct knote *kn)
*/
if ((kn->kn_flags & EV_FLAG1) == 0)
return (EPERM);
kn->kn_ptr.p_aio = aiocbe;
kn->kn_flags &= ~EV_FLAG1;
knlist_add(&aiocbe->klist, kn, 0);
@ -2262,7 +2263,7 @@ filt_aioattach(struct knote *kn)
static void
filt_aiodetach(struct knote *kn)
{
struct aiocblist *aiocbe = (struct aiocblist *)kn->kn_sdata;
struct aiocblist *aiocbe = kn->kn_ptr.p_aio;
if (!knlist_empty(&aiocbe->klist))
knlist_remove(&aiocbe->klist, kn, 0);
@ -2273,7 +2274,7 @@ filt_aiodetach(struct knote *kn)
static int
filt_aio(struct knote *kn, long hint)
{
struct aiocblist *aiocbe = (struct aiocblist *)kn->kn_sdata;
struct aiocblist *aiocbe = kn->kn_ptr.p_aio;
kn->kn_data = aiocbe->uaiocb._aiocb_private.error;
if (aiocbe->jobstate != JOBST_JOBFINISHED)
@ -2295,6 +2296,7 @@ filt_lioattach(struct knote *kn)
*/
if ((kn->kn_flags & EV_FLAG1) == 0)
return (EPERM);
kn->kn_ptr.p_lio = lj;
kn->kn_flags &= ~EV_FLAG1;
knlist_add(&lj->klist, kn, 0);
@ -2306,7 +2308,7 @@ filt_lioattach(struct knote *kn)
static void
filt_liodetach(struct knote *kn)
{
struct aioliojob * lj = (struct aioliojob *)kn->kn_sdata;
struct aioliojob * lj = kn->kn_ptr.p_lio;
if (!knlist_empty(&lj->klist))
knlist_remove(&lj->klist, kn, 0);
@ -2317,7 +2319,7 @@ filt_liodetach(struct knote *kn)
static int
filt_lio(struct knote *kn, long hint)
{
struct aioliojob * lj = (struct aioliojob *)kn->kn_sdata;
struct aioliojob * lj = kn->kn_ptr.p_lio;
return (lj->lioj_flags & LIOJ_KEVENT_POSTED);
}

2
sys/sys/event.h
View File

@ -181,6 +181,8 @@ struct knote {
union {
struct file *p_fp; /* file data pointer */
struct proc *p_proc; /* proc pointer */
struct aiocblist *p_aio; /* AIO job pointer */
struct aioliojob *p_lio; /* LIO job pointer */
} kn_ptr;
struct filterops *kn_fop;
void *kn_hook;