Re: [BUG RESEND] [BISECTED]: selftest: ftracetest: memleak in vfs_write()

[Eric Biggers]

Hi Mirsad,

On Tue, Apr 04, 2023 at 09:52:10PM +0200, Mirsad Goran Todorovac wrote:
>   backtrace:
>     [<ffffffffb4afb23c>] slab_post_alloc_hook+0x8c/0x3e0
>     [<ffffffffb4b02b19>] __kmem_cache_alloc_node+0x1d9/0x2a0
>     [<ffffffffb4a77785>] __kmalloc+0x55/0x160
>     [<ffffffffb493a913>] tracing_log_err+0x1a3/0x1d0
>     [<ffffffffb4959049>] append_filter_err.isra.13+0x119/0x190
>     [<ffffffffb495a89f>] create_filter+0xbf/0xe0
>     [<ffffffffb495ab10>] create_event_filter+0x10/0x20
>     [<ffffffffb495c040>] set_trigger_filter+0xa0/0x180
>     [<ffffffffb495d745>] event_trigger_parse+0xf5/0x160
>     [<ffffffffb495c889>] trigger_process_regex+0xc9/0x120
>     [<ffffffffb495c976>] event_trigger_write+0x86/0xf0
>     [<ffffffffb4b52dc2>] vfs_write+0xf2/0x520
>     [<ffffffffb4b533d8>] ksys_write+0x68/0xe0
>     [<ffffffffb4b5347e>] __x64_sys_write+0x1e/0x30
>     [<ffffffffb586619c>] do_syscall_64+0x5c/0x90
>     [<ffffffffb5a000ae>] entry_SYSCALL_64_after_hwframe+0x72/0xdc
> 
> Please find the complete debug info at the URL:
> 
> https://domac.alu.unizg.hr/~mtodorov/linux/bugreports/ftracetest/
> 
> Bisect log is [edited]:
> 
> > git bisect good a92ce570c81dc0feaeb12a429b4bc65686d17967
> > # good: [c6f613e5f35b0e2154d5ca12f0e8e0be0c19be9a] ipmi/watchdog: use strscpy() to instead of strncpy()
> > git bisect good c6f613e5f35b0e2154d5ca12f0e8e0be0c19be9a
> > # good: [90b12f423d3c8a89424c7bdde18e1923dfd0941e] Merge tag 'for-linus-6.2-1' of https://github.com/cminyard/linux-ipmi
> > git bisect good 90b12f423d3c8a89424c7bdde18e1923dfd0941e
> > # first bad commit: [71946a25f357a51dcce849367501d7fb04c0465b] Merge tag 'mmc-v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc
> > 
> > The commit was merged on December 13th 2022.
> 
> The amount of applied diffs in the culprit commit 71946a25f357a51dcce849367501d7fb04c0465b
> prevents me from bisecting further - I do not know which changes depend of which, and which
> can be tested independently.
> 
> Hopefully I might come up with a reproducer, but I need some feedback first. Maybe there
> are ways to narrow down the lines of code that could have caused the leaks, yet I am
> completely new to the kernel/trace subtree.
> 
> Apologies for not Cc:ing Ulf nine weeks ago, but it was an omission, not deliberate act.
> 

This looks like an issue with the tracing subsystem.  I appreciate that you've
now added the tracing maintainers to Cc.  I don't think your bisection to commit
71946a25f357 ("Merge tag 'mmc-v6.2' ...") is correct; that looks unrelated.

- Eric