[PATCH 3.17 011/141] net: ppp: Dont call bpf_prog_create() in ppp_lock

Greg Kroah-Hartman
2014-11-19T22:41:41Z

From: Takashi Iwai <tiwai@suse.de>

[ Upstream commit 5748eb8f8e989a9da1ac7c96dc73d68cbdedf7df ]

In ppp_ioctl(), bpf_prog_create() is called inside ppp_lock, which
eventually calls vmalloc() and hits BUG_ON() in vmalloc.c. This patch
works around the problem by moving the allocation outside the lock.

The bug was revealed by the recent change in net/core/filter.c, as it
allocates via vmalloc() instead of kmalloc() now.

Reported-and-tested-by: Stefan Seyfried <stefan.seyfried@googlemail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ppp/ppp_generic.c | 40 ++++++++++++++++++++--------------------
1 file changed, 20 insertions(+), 20 deletions(-)

--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -755,23 +755,23 @@ static long ppp_ioctl(struct file *file,

err = get_filter(argp, &code);
if (err >= 0) {
+ struct bpf_prog *pass_filter = NULL;
struct sock_fprog_kern fprog = {
.len = err,
.filter = code,
};

- ppp_lock(ppp);
- if (ppp->pass_filter) {
- bpf_prog_destroy(ppp->pass_filter);
- ppp->pass_filter = NULL;
+ err = 0;
+ if (fprog.filter)
+ err = bpf_prog_create(&pass_filter, &fprog);
+ if (!err) {
+ ppp_lock(ppp);
+ if (ppp->pass_filter)
+ bpf_prog_destroy(ppp->pass_filter);
+ ppp->pass_filter = pass_filter;
+ ppp_unlock(ppp);
}
- if (fprog.filter != NULL)
- err = bpf_prog_create(&ppp->pass_filter,
- &fprog);
- else
- err = 0;
kfree(code);
- ppp_unlock(ppp);
}
break;
}
@@ -781,23 +781,23 @@ static long ppp_ioctl(struct file *file,

err = get_filter(argp, &code);
if (err >= 0) {
+ struct bpf_prog *active_filter = NULL;
struct sock_fprog_kern fprog = {
.len = err,
.filter = code,
};

- ppp_lock(ppp);
- if (ppp->active_filter) {
- bpf_prog_destroy(ppp->active_filter);
- ppp->active_filter = NULL;
+ err = 0;
+ if (fprog.filter)
+ err = bpf_prog_create(&active_filter, &fprog);
+ if (!err) {
+ ppp_lock(ppp);
+ if (ppp->active_filter)
+ bpf_prog_destroy(ppp->active_filter);
+ ppp->active_filter = active_filter;
+ ppp_unlock(ppp);
}
- if (fprog.filter != NULL)
- err = bpf_prog_create(&ppp->active_filter,
- &fprog);
- else
- err = 0;
kfree(code);
- ppp_unlock(ppp);
}
break;
}