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SubjectRe: [PATCH] coresight: tmc-etf: Fix global-out-of-bounds in tmc_update_etf_buffer()
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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")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
> ---
> drivers/hwtracing/coresight/coresight-tmc-etf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etf.c b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> index 45b85edfc690..cd0fb7bfba68 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etf.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etf.c
> @@ -530,7 +530,7 @@ static unsigned long tmc_update_etf_buffer(struct coresight_device *csdev,
> buf_ptr = buf->data_pages[cur] + offset;
> *buf_ptr = readl_relaxed(drvdata->base + TMC_RRD);
>
> - if (lost && *barrier) {
> + if (lost && i < CORESIGHT_BARRIER_PKT_SIZE) {
> *buf_ptr = *barrier;
> barrier++;
> }
>

Thanks for the fix. I will queue this one after rc1

Thanks
Suzuki

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