ACK/Cmnt: [SRU][F/J/M][PATCH 0/2] CVE-2024-26624
Stefan Bader
stefan.bader at canonical.com
Wed Mar 27 15:11:15 UTC 2024
On 27.03.24 01:18, Yuxuan Luo wrote:
> [Impact]
> A potential deadlock is found in the AF_UNIX subsystem, the scenario is
> shown below:
>
> CPU0 CPU1
> ---- ----
> lock(&u->lock/1);
> lock(rlock-AF_UNIX);
> lock(&u->lock/1);
> lock(rlock-AF_UNIX);
>
> *** DEADLOCK ***
> Such deadlock could lead to serious denial of service and system crash.
>
> [Backport]
> The fix is a clean cherry pick.
>
> However, the modified function has been copied to our own trees
> (security/apparmor/af_unix.c), therefore, a sauce patch is needed to
> synchronize the change.
>
> [Test]
> Compile and boot tested.
>
> [Where things could go wrong]
> The fix touches af_unix.c which means most of the use case are affected.
> However, what this fix does is to add "an identifier" to the locks to
> avoid potential deadlock without touching working logic; plus, this fix
> has been backported to multiple stable trees, expect very low regression
> potential. If such happens, it is probably a denial of service.
>
> Eric Dumazet (1):
> af_unix: fix lockdep positive in sk_diag_dump_icons()
>
> Yuxuan Luo (1):
> UBUNTU: SAUCE: af_unix: fix lockdep positive in sk_diag_dump_icons()
>
> include/net/af_unix.h | 20 ++++++++++++++------
> net/unix/af_unix.c | 14 ++++++--------
> net/unix/diag.c | 2 +-
> security/apparmor/af_unix.c | 12 +++++-------
> 4 files changed, 26 insertions(+), 22 deletions(-)
>
I would adjust the commit message of the second patch a bit to make it
less look like something taken from upstream and try to clarify the
dependency a little better.
Acked-by: Stefan Bader <stefan.bader at canonical.com>
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