NetBSD Problem Report #49386
From www@NetBSD.org Wed Nov 12 03:16:26 2014
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for <gnats-bugs@gnats.NetBSD.org>; Wed, 12 Nov 2014 03:16:26 +0000 (UTC)
Message-Id: <20141112031624.AD10EA66A2@mollari.NetBSD.org>
Date: Wed, 12 Nov 2014 03:16:24 +0000 (UTC)
From: ozaki-r@netbsd.org
Reply-To: ozaki-r@netbsd.org
To: gnats-bugs@NetBSD.org
Subject: Possible panics on bpf attach/detach
X-Send-Pr-Version: www-1.0
>Number: 49386
>Category: kern
>Synopsis: Possible panics on bpf attach/detach
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: kern-bug-people
>State: closed
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Wed Nov 12 03:20:00 +0000 2014
>Closed-Date: Sat Jun 16 23:46:27 +0000 2018
>Last-Modified: Sat Jun 16 23:46:27 +0000 2018
>Originator: Ryota Ozaki
>Release: current
>Organization:
>Environment:
NetBSD kvm 7.99.1 NetBSD 7.99.1 (GENERIC.201411100400Z) #0: Mon Nov 10 04:55:44 UTC 2014 snj@b45.netbsd.org:/home/builds/ab/HEAD/amd64/201411100400Z-obj/home/source/ab/HEAD/src/sys/arch/amd64/compile/GENERIC amd64
>Description:
bpf is racy on attach and detach. We encounter the following panics
although they're very rare cases.
# panic#1
uvm_fault(0xfffffe8001fea2e0, 0x0, 1) -> e
fatal page fault in supervisor mode
trap type 6 code 0 rip ffffffff803e8802 cs 8 rflags 10246 cr2 39 ilevel 6 rsp fffffe8002463d70
curlwp 0xfffffe8002041600 pid 2338.1 lowest kstack 0xfffffe80024602c0
kernel: page fault trap, code=0
Stopped in pid 2338.1 (tcpdump) at netbsd:ifpromisc+0xa: movl 38(%rdi)
,%r12d
db{2}> bt
ifpromisc() at netbsd:ifpromisc+0xa
bpf_ioctl() at netbsd:bpf_ioctl+0x825
sys_ioctl() at netbsd:sys_ioctl+0x17e
syscall() at netbsd:syscall+0x9a
--- syscall (number 54) ---
7f7ff66cea0a:
# panic#2
uvm_fault(0xfffffe800319d468, 0x700000000, 2) -> e
fatal page fault in supervisor mode
trap type 6 code 2 rip ffffffff80219327 cs 8 rflags 10246 cr2 700000006 ilevel 6 rsp fffffe8001fbed90
curlwp 0xfffffe8002eca6e0 pid 792.1 lowest kstack 0xfffffe8001fbb2c0
kernel: page fault trap, code=0
Stopped in pid 792.1 (tcpdump) at netbsd:bpf_ioctl+0x75f: movq %r12,0(%
rax)
db{2}> bt
bpf_ioctl() at netbsd:bpf_ioctl+0x75f
sys_ioctl() at netbsd:sys_ioctl+0x17e
syscall() at netbsd:syscall+0x9a
--- syscall (number 54) ---
7f7ff66cea0a:
>How-To-Repeat:
The below script causes the above panic on KVM with 4 VCPUs.
A different machine would require different parameters.
#!/bin/sh
IF0=vioif0
IF1=vioif1
tap_create()
{
name=$1
ifconfig $name create
ifconfig $name up
}
tap_destroy()
{
name=$1
ifconfig $name destroy
}
while true; do tcpdump -n -i $IF0 -c 10 > /dev/null 2>&1; done &
while true; do tcpdump -n -i $IF0 -c 10 > /dev/null 2>&1; done &
while true; do tcpdump -n -i $IF1 -c 10 > /dev/null 2>&1; done &
while true; do tcpdump -n -i $IF1 -c 10 > /dev/null 2>&1; done &
while true; do
tap_create tap0 &
for i in $(seq 0 2); do
tcpdump -n -i tap0 -c 10 > /dev/null 2>&1 &
done
pkill tcpdump
tap_destroy tap0 &
done
# EOF
>Fix:
diff --git a/sys/net/bpf.c b/sys/net/bpf.c
index f66e783..2e68ad1 100644
--- a/sys/net/bpf.c
+++ b/sys/net/bpf.c
@@ -340,6 +340,7 @@ bad:
static void
bpf_attachd(struct bpf_d *d, struct bpf_if *bp)
{
+ KASSERT(mutex_owned(&bpf_mtx));
/*
* Point d at bp, and add d to the interface's list of listeners.
* Finally, point the driver's bpf cookie at the interface so
@@ -361,6 +362,8 @@ bpf_detachd(struct bpf_d *d)
struct bpf_d **p;
struct bpf_if *bp;
+ KASSERT(mutex_owned(&bpf_mtx));
+
bp = d->bd_bif;
/*
* Check if this descriptor had requested promiscuous mode.
@@ -476,6 +479,7 @@ bpf_close(struct file *fp)
int s;
KERNEL_LOCK(1, NULL);
+ mutex_enter(&bpf_mtx);
/*
* Refresh the PID associated with this bpf file.
@@ -490,15 +494,14 @@ bpf_close(struct file *fp)
bpf_detachd(d);
splx(s);
bpf_freed(d);
- mutex_enter(&bpf_mtx);
LIST_REMOVE(d, bd_list);
- mutex_exit(&bpf_mtx);
callout_destroy(&d->bd_callout);
seldestroy(&d->bd_sel);
softint_disestablish(d->bd_sih);
free(d, M_DEVBUF);
fp->f_bpf = NULL;
+ mutex_exit(&bpf_mtx);
KERNEL_UNLOCK_ONE(NULL);
return (0);
@@ -900,10 +903,12 @@ bpf_ioctl(struct file *fp, u_long cmd, void *addr)
* Set device parameters.
*/
case BIOCSDLT:
+ mutex_enter(&bpf_mtx);
if (d->bd_bif == NULL)
error = EINVAL;
else
error = bpf_setdlt(d, *(u_int *)addr);
+ mutex_exit(&bpf_mtx);
break;
/*
@@ -926,7 +931,9 @@ bpf_ioctl(struct file *fp, u_long cmd, void *addr)
case OBIOCSETIF:
#endif
case BIOCSETIF:
+ mutex_enter(&bpf_mtx);
error = bpf_setif(d, addr);
+ mutex_exit(&bpf_mtx);
break;
/*
@@ -1152,6 +1159,7 @@ bpf_setif(struct bpf_d *d, struct ifreq *ifr)
char *cp;
int unit_seen, i, s, error;
+ KASSERT(mutex_owned(&bpf_mtx));
/*
* Make sure the provided name has a unit number, and default
* it to '0' if not specified.
@@ -1718,10 +1726,10 @@ static int
bpf_allocbufs(struct bpf_d *d)
{
- d->bd_fbuf = malloc(d->bd_bufsize, M_DEVBUF, M_WAITOK | M_CANFAIL);
+ d->bd_fbuf = malloc(d->bd_bufsize, M_DEVBUF, M_NOWAIT);
if (!d->bd_fbuf)
return (ENOBUFS);
- d->bd_sbuf = malloc(d->bd_bufsize, M_DEVBUF, M_WAITOK | M_CANFAIL);
+ d->bd_sbuf = malloc(d->bd_bufsize, M_DEVBUF, M_NOWAIT);
if (!d->bd_sbuf) {
free(d->bd_fbuf, M_DEVBUF);
return (ENOBUFS);
@@ -1771,6 +1779,7 @@ _bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen, struct bpf_if **driverp)
if (bp == NULL)
panic("bpfattach");
+ mutex_enter(&bpf_mtx);
bp->bif_dlist = NULL;
bp->bif_driverp = driverp;
bp->bif_ifp = ifp;
@@ -1782,6 +1791,7 @@ _bpfattach(struct ifnet *ifp, u_int dlt, u_int hdrlen, struct bpf_if **driverp)
*bp->bif_driverp = NULL;
bp->bif_hdrlen = hdrlen;
+ mutex_exit(&bpf_mtx);
#if 0
printf("bpf: %s attached\n", ifp->if_xname);
#endif
@@ -1797,6 +1807,7 @@ _bpfdetach(struct ifnet *ifp)
struct bpf_d *d;
int s;
+ mutex_enter(&bpf_mtx);
/* Nuke the vnodes for any open instances */
LIST_FOREACH(d, &bpf_list, bd_list) {
if (d->bd_bif != NULL && d->bd_bif->bif_ifp == ifp) {
@@ -1820,6 +1831,7 @@ _bpfdetach(struct ifnet *ifp)
goto again;
}
}
+ mutex_exit(&bpf_mtx);
}
/*
@@ -1880,6 +1892,8 @@ bpf_setdlt(struct bpf_d *d, u_int dlt)
struct ifnet *ifp;
struct bpf_if *bp;
+ KASSERT(mutex_owned(&bpf_mtx));
+
if (d->bd_bif->bif_dlt == dlt)
return 0;
ifp = d->bd_bif->bif_ifp;
>Release-Note:
>Audit-Trail:
From: "Christos Zoulas" <christos@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc:
Subject: PR/49386 CVS commit: src/sys/net
Date: Wed, 14 Oct 2015 15:40:10 -0400
Module Name: src
Committed By: christos
Date: Wed Oct 14 19:40:09 UTC 2015
Modified Files:
src/sys/net: bpf.c
Log Message:
PR/49386: Ryota Ozaki: Add a mutex for bpf creation/removal to avoid races.
Add M_CANFAIL to malloc.
To generate a diff of this commit:
cvs rdiff -u -r1.191 -r1.192 src/sys/net/bpf.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
State-Changed-From-To: open->closed
State-Changed-By: dholland@NetBSD.org
State-Changed-When: Sat, 16 Jun 2018 23:46:27 +0000
State-Changed-Why:
committed by christos in 2015
>Unformatted:
(Contact us)
$NetBSD: query-full-pr,v 1.43 2018/01/16 07:36:43 maya Exp $
$NetBSD: gnats_config.sh,v 1.9 2014/08/02 14:16:04 spz Exp $
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