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ppp: fix out-of-bounds access in bpf_prog_create()

Message ID 20191205055419.13435-1-ebiggers@kernel.org (mailing list archive)
State New, archived
Headers show
Series ppp: fix out-of-bounds access in bpf_prog_create() | expand

Commit Message

Eric Biggers Dec. 5, 2019, 5:54 a.m. UTC 
From: Eric Biggers <ebiggers@google.com>

sock_fprog_kern::len is in units of struct sock_filter, not bytes.

Fixes: 3e859adf3643 ("compat_ioctl: unify copy-in of ppp filters")
Reported-by: syzbot+eb853b51b10f1befa0b7@syzkaller.appspotmail.com
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 drivers/net/ppp/ppp_generic.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

Comments

Arnd Bergmann Dec. 5, 2019, 9:07 a.m. UTC | #1 
On Thu, Dec 5, 2019 at 6:55 AM Eric Biggers <ebiggers@kernel.org> wrote:
>
> From: Eric Biggers <ebiggers@google.com>
>
> sock_fprog_kern::len is in units of struct sock_filter, not bytes.
>
> Fixes: 3e859adf3643 ("compat_ioctl: unify copy-in of ppp filters")
> Reported-by: syzbot+eb853b51b10f1befa0b7@syzkaller.appspotmail.com
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Reviewed-by: Arnd Bergmann <arnd@arndb.de>

Thanks for fixing the bug I introduced!
David Miller Dec. 5, 2019, 10:45 p.m. UTC | #2 
From: Eric Biggers <ebiggers@kernel.org>
Date: Wed,  4 Dec 2019 21:54:19 -0800

> From: Eric Biggers <ebiggers@google.com>
> 
> sock_fprog_kern::len is in units of struct sock_filter, not bytes.
> 
> Fixes: 3e859adf3643 ("compat_ioctl: unify copy-in of ppp filters")
> Reported-by: syzbot+eb853b51b10f1befa0b7@syzkaller.appspotmail.com
> Signed-off-by: Eric Biggers <ebiggers@google.com>

Applied, thank you.
diff mbox series

Patch

diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c
index 0cb1c2d0a8bc..3bf8a8b42983 100644
--- a/drivers/net/ppp/ppp_generic.c
+++ b/drivers/net/ppp/ppp_generic.c
@@ -564,8 +564,9 @@  static struct bpf_prog *get_filter(struct sock_fprog *uprog)
 		return NULL;
 
 	/* uprog->len is unsigned short, so no overflow here */
-	fprog.len = uprog->len * sizeof(struct sock_filter);
-	fprog.filter = memdup_user(uprog->filter, fprog.len);
+	fprog.len = uprog->len;
+	fprog.filter = memdup_user(uprog->filter,
+				   uprog->len * sizeof(struct sock_filter));
 	if (IS_ERR(fprog.filter))
 		return ERR_CAST(fprog.filter);