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Date:      Thu, 02 Feb 2023 17:42:34 +0000
From:      bugzilla-noreply@freebsd.org
To:        net@FreeBSD.org
Subject:   [Bug 266442] kernel page fault on packet with broken lengths if ipfilter is loaded
Message-ID:  <bug-266442-7501-1jJpxKBOhV@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-266442-7501@https.bugs.freebsd.org/bugzilla/>
References:  <bug-266442-7501@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D266442

--- Comment #6 from commit-hook@FreeBSD.org ---
A commit in branch main references this bug:

URL:
https://cgit.FreeBSD.org/src/commit/?id=3D79f7745c098a766d34a4e072cdd1a06e6=
d0829d5

commit 79f7745c098a766d34a4e072cdd1a06e6d0829d5
Author:     Cy Schubert <cy@FreeBSD.org>
AuthorDate: 2023-02-02 00:49:08 +0000
Commit:     Cy Schubert <cy@FreeBSD.org>
CommitDate: 2023-02-02 17:41:22 +0000

    ipfilter: Fix use after free on packet with broken lengths

    Under the scenario with a packet with length of 67 bytes, a header leng=
th
    using the default of 20 bytes and a TCP data offset (th_off) of 48 will
    cause m_pullup() to fail to make sure bytes are arragned contiguously.
    m_pullup() will free the mbuf chain and return a null. ipfilter stores
    the resultant mbuf address (or the resulting NULL) in its fr_info_t
    structure. Unfortuntely the eroneous packet is not flagged for drop.
    This results in a kernel page fault at line 410 of sys/netinet/ip_fastf=
wd.c
    as it tries to use a now previously freed, by m_pullup(), mbuf.

    PR:             266442
    Reported by:    Robert Morris <rtm@lcs.mit.edu>
    MFC after:      1 week

 sys/netpfil/ipfilter/netinet/fil.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

--=20
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