Re: [PATCH] coresight: tmc-etf: Fix global-out-of-bounds in tmc_update_etf_buffer()

[Suzuki K Poulose]

Hi Sai

On 05/05/2021 10:47, Suzuki K Poulose wrote:
> On 05/05/2021 10:34, Sai Prakash Ranjan wrote:
> > commit 6f755e85c332 ("coresight: Add helper for inserting synchronization
> > packets") removed trailing '\0' from barrier_pkt array and updated the
> > call sites like etb_update_buffer() to have proper checks for barrier_pkt
> > size before read but missed updating tmc_update_etf_buffer() which still
> > reads barrier_pkt past the array size resulting in KASAN out-of-bounds
> > bug. Fix this by adding a check for barrier_pkt size before accessing
> > like it is done in etb_update_buffer().
> >
> >   BUG: KASAN: global-out-of-bounds in tmc_update_etf_buffer+0x4b8/0x698
> >   Read of size 4 at addr ffffffd05b7d1030 by task perf/2629
> >
> >   Call trace:
> >    dump_backtrace+0x0/0x27c
> >    show_stack+0x20/0x2c
> >    dump_stack+0x11c/0x188
> >    print_address_description+0x3c/0x4a4
> >    __kasan_report+0x140/0x164
> >    kasan_report+0x10/0x18
> >    __asan_report_load4_noabort+0x1c/0x24
> >    tmc_update_etf_buffer+0x4b8/0x698
> >    etm_event_stop+0x248/0x2d8
> >    etm_event_del+0x20/0x2c
> >    event_sched_out+0x214/0x6f0
> >    group_sched_out+0xd0/0x270
> >    ctx_sched_out+0x2ec/0x518
> >    __perf_event_task_sched_out+0x4fc/0xe6c
> >    __schedule+0x1094/0x16a0
> >    preempt_schedule_irq+0x88/0x170
> >    arm64_preempt_schedule_irq+0xf0/0x18c
> >    el1_irq+0xe8/0x180
> >    perf_event_exec+0x4d8/0x56c
> >    setup_new_exec+0x204/0x400
> >    load_elf_binary+0x72c/0x18c0
> >    search_binary_handler+0x13c/0x420
> >    load_script+0x500/0x6c4
> >    search_binary_handler+0x13c/0x420
> >    exec_binprm+0x118/0x654
> >    __do_execve_file+0x77c/0xba4
> >    __arm64_compat_sys_execve+0x98/0xac
> >    el0_svc_common+0x1f8/0x5e0
> >    el0_svc_compat_handler+0x84/0xb0
> >    el0_svc_compat+0x10/0x50
> >
> >   The buggy address belongs to the variable:
> >    barrier_pkt+0x10/0x40
> >
> >   Memory state around the buggy address:
> >    ffffffd05b7d0f00: fa fa fa fa 04 fa fa fa fa fa fa fa 00 00 00 00
> >    ffffffd05b7d0f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> >   >ffffffd05b7d1000: 00 00 00 00 00 00 fa fa fa fa fa fa 00 00 00 03
> >                                        ^
> >    ffffffd05b7d1080: fa fa fa fa 00 02 fa fa fa fa fa fa 03 fa fa fa
> >    ffffffd05b7d1100: fa fa fa fa 00 00 00 00 05 fa fa fa fa fa fa fa
> >   ==================================================================
> >
> > Fixes: 6f755e85c332 ("coresight: Add helper for inserting 
> > synchronization packets")

I have changed the commit to :

Fixes: 0c3fc4d5fa26 ("coresight: Add barrier packet for synchronisation")

Applied.

Thanks
Suzuki