Re: [PATCH] perf: Fix slab use-after-free in filter_chain

[sashiko-bot@kernel.org]

> Syzbot reported a slab use-after-free read in uprobe_mmap. The root cause is
> when a trace_probe has a sibling event, unregister_trace_uprobe() does
> not unlink &tu->consumer. This memory can still be referenced in
> multiple locations, namely filter_chain and uprobe_mmap, resulting in a
> use-after-free. This is not a security issue as creating uprobes
> requires CAP_SYS_ADMIN.
> 
> Here's a short repro in bash which will trigger a KASAN report, tested on
> v7.2.4. Note the offsets used for /bin/true may need some adjusting,
> they are the offset of its entrypoint in this example:
> ```
> echo "p:uprobe_test/evS /bin/true:0x23d0" >> /sys/kernel/tracing/uprobe_events
> echo "p:uprobe_test/evS /bin/true:0x23d4" >> /sys/kernel/tracing/uprobe_events
> echo 1 > /sys/kernel/tracing/events/uprobe_test/evS/enable
> echo "-:uprobe_test/evS" >> /sys/kernel/tracing/uprobe_events
> /bin/true
> ```
> 
> This is my first time sending a patch to the linux kernel mailing list,
> apologies if there are any mistakes.
> 
> Reported-by: syzbot+1340ad4350ad43394c10@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=1340ad4350ad43394c10
> Signed-off-by: Zafir Rasyidi Taufik <zafir.taufik@starlabs.sg>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260908023223.1516819-2-zafir.taufik@starlabs.sg?part=1