linux-kernel - Re: [PATCH] coresight: tmc: sg: Do not leak sg

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Message-ID: <b09ab9be-2f7f-4a2c-9012-5d8d26bba93d@arm.com>
Date: Thu, 4 Jul 2024 09:29:26 +0530
From: Anshuman Khandual <anshuman.khandual@....com>
To: Suzuki K Poulose <suzuki.poulose@....com>, coresight@...ts.linaro.org
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 mike.leach@...aro.org, James Clark <james.clark@....com>
Subject: Re: [PATCH] coresight: tmc: sg: Do not leak sg_table


On 7/2/24 18:58, Suzuki K Poulose wrote:
> Running perf with cs_etm on Juno triggers the following kmemleak warning !
> 
> :~# cat /sys/kernel/debug/kmemleak
>  unreferenced object 0xffffff8806b6d720 (size 96):
>  comm "perf", pid 562, jiffies 4297810960
>  hex dump (first 32 bytes):
>  38 d8 13 07 88 ff ff ff 00 d0 9e 85 c0 ff ff ff  8...............
>  00 10 00 88 c0 ff ff ff 00 f0 ff f7 ff 00 00 00  ................
>  backtrace (crc 1dbf6e00):
>  [<ffffffc08107381c>] kmemleak_alloc+0xbc/0xd8
>  [<ffffffc0802f9798>] kmalloc_trace_noprof+0x220/0x2e8
>  [<ffffffc07bb71948>] tmc_alloc_sg_table+0x48/0x208 [coresight_tmc]
>  [<ffffffc07bb71cbc>] tmc_etr_alloc_sg_buf+0xac/0x240 [coresight_tmc]
>  [<ffffffc07bb72538>] tmc_alloc_etr_buf.constprop.0+0x1f0/0x260 [coresight_tmc]
>  [<ffffffc07bb7280c>] alloc_etr_buf.constprop.0.isra.0+0x74/0xa8 [coresight_tmc]
>  [<ffffffc07bb72950>] tmc_alloc_etr_buffer+0x110/0x260 [coresight_tmc]
>  [<ffffffc07bb38afc>] etm_setup_aux+0x204/0x3b0 [coresight]
>  [<ffffffc08025837c>] rb_alloc_aux+0x20c/0x318
>  [<ffffffc08024dd84>] perf_mmap+0x2e4/0x7a0
>  [<ffffffc0802cceb0>] mmap_region+0x3b0/0xa08
>  [<ffffffc0802cd8a8>] do_mmap+0x3a0/0x500
>  [<ffffffc080295328>] vm_mmap_pgoff+0x100/0x1d0
>  [<ffffffc0802cadf8>] ksys_mmap_pgoff+0xb8/0x110
>  [<ffffffc080020688>] __arm64_sys_mmap+0x38/0x58
>  [<ffffffc080028fc0>] invoke_syscall.constprop.0+0x58/0x100
> 
> This due to the fact that we do not free the "sg_table" itself while
> freeing up  the SG table and data pages. Fix this by freeing the sg_table
> in tmc_free_sg_table().
> 
> Fixes: 99443ea19e8b ("coresight: Add generic TMC sg table framework")
> Cc: Mike Leach <mike.leach@...aro.org>
> Cc: James Clark <james.clark@....com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>

LGTM

Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>

> ---
>  drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index e75428fa1592..610ad51cda65 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -261,6 +261,7 @@ void tmc_free_sg_table(struct tmc_sg_table *sg_table)
>  {
>  	tmc_free_table_pages(sg_table);
>  	tmc_free_data_pages(sg_table);
> +	kfree(sg_table);
>  }
>  EXPORT_SYMBOL_GPL(tmc_free_sg_table);
>  
> @@ -342,7 +343,6 @@ struct tmc_sg_table *tmc_alloc_sg_table(struct device *dev,
>  		rc = tmc_alloc_table_pages(sg_table);
>  	if (rc) {
>  		tmc_free_sg_table(sg_table);
> -		kfree(sg_table);
>  		return ERR_PTR(rc);
>  	}
>