Re: CVE-2023-52734: net: sched: sch: Bounds check priority

[Michal Hocko]

Is this really soemthing that should be getting a CVE assigned?
First the fix is incomplete - 9cec2aaffe96 ("net: sched: sch: Fix off by one in htb_activate_prios()")
Second is this even real problem? https://lore.kernel.org/all/Y9V3mBmLUcrEdrTV@pop-os.localdomain/
suggests it is not.

And third, WARN_ONs are considered a real deal by CVE team because
somebody might be running with panic_on_warn. This patch adds one!

On Tue 21-05-24 17:23:11, Greg KH wrote:
> Description
> ===========
> 
> In the Linux kernel, the following vulnerability has been resolved:
> 
> net: sched: sch: Bounds check priority
> 
> Nothing was explicitly bounds checking the priority index used to access
> clpriop[]. WARN and bail out early if it's pathological. Seen with GCC 13:
> 
> ../net/sched/sch_htb.c: In function 'htb_activate_prios':
> ../net/sched/sch_htb.c:437:44: warning: array subscript [0, 31] is outside array bounds of 'struct htb_prio[8]' [-Warray-bounds=]
>   437 |                         if (p->inner.clprio[prio].feed.rb_node)
>       |                             ~~~~~~~~~~~~~~~^~~~~~
> ../net/sched/sch_htb.c:131:41: note: while referencing 'clprio'
>   131 |                         struct htb_prio clprio[TC_HTB_NUMPRIO];
>       |                                         ^~~~~~
> 
> The Linux kernel CVE team has assigned CVE-2023-52734 to this issue.
> 
> 
> Affected and fixed versions
> ===========================
> 
> 	Fixed in 5.4.232 with commit fbe71c5dacaa
> 	Fixed in 5.10.169 with commit 90fcf55d83b2
> 	Fixed in 5.15.95 with commit 99875ea9b5b4
> 	Fixed in 6.1.13 with commit f6415c9c9a0b
> 	Fixed in 6.2 with commit de5ca4c3852f
> 
> Please see https://www.kernel.org for a full list of currently supported
> kernel versions by the kernel community.
> 
> Unaffected versions might change over time as fixes are backported to
> older supported kernel versions.  The official CVE entry at
> 	https://cve.org/CVERecord/?id=CVE-2023-52734
> will be updated if fixes are backported, please check that for the most
> up to date information about this issue.
> 
> 
> Affected files
> ==============
> 
> The file(s) affected by this issue are:
> 	net/sched/sch_htb.c
> 
> 
> Mitigation
> ==========
> 
> The Linux kernel CVE team recommends that you update to the latest
> stable kernel version for this, and many other bugfixes.  Individual
> changes are never tested alone, but rather are part of a larger kernel
> release.  Cherry-picking individual commits is not recommended or
> supported by the Linux kernel community at all.  If however, updating to
> the latest release is impossible, the individual changes to resolve this
> issue can be found at these commits:
> 	https://git.kernel.org/stable/c/fbe71c5dacaa5a9960323215f118958174c81aa0
> 	https://git.kernel.org/stable/c/90fcf55d83b20da1091f926a291af05fb74f61c6
> 	https://git.kernel.org/stable/c/99875ea9b5b47995bfb3c684d21eb17feb4b7e6a
> 	https://git.kernel.org/stable/c/f6415c9c9a0b3881543d38528a58b54af4351522
> 	https://git.kernel.org/stable/c/de5ca4c3852f896cacac2bf259597aab5e17d9e3

-- 
Michal Hocko
SUSE Labs