Messages in this thread | | | Date | Mon, 24 Jul 2023 16:38:10 +0100 | Subject | Re: [RESEND PATCH] coresight: tmc: Explicit type conversions to prevent integer overflow | From | James Clark <> |
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On 14/07/2023 09:43, Ruidong Tian wrote: > Perf cs_etm session will failed when AUX buffer > 1G. > > perf record -C 0 -m ,2G -e cs_etm// -- taskset -c 0 ls > failed to mmap with 12 (Cannot allocate memory) > > In coresight tmc driver, "nr_pages << PAGE_SHIFT" will overflow when > nr_pages >= 0x80000(correspond to 1G AUX buffer). Explicit convert nr_pages > to 64 bit to avoid overflow. >
Hi Ruidong,
I couldn't reproduce this exact issue with the error message in the commit message. Is it not another manifestation related to this change [1]? I don't actually get any error message, but I was able to get a warning in dmesg even with [1] applied.
Does the overflow not result in a successful session but with the wrong buffer size?
I think the change makes sense, but maybe we also need a check for MAX_ORDER because I can trigger the same WARN_ON from [1]. Or maybe I'm a bit confused because of the other change and not being able to reproduce this exactly coming at the same time.
[1]: https://lore.kernel.org/bpf/20230711014120.53461-1-xueshuai@linux.alibaba.com/
Thanks James
> Signed-off-by: Ruidong Tian <tianruidong@linux.alibaba.com> > --- > drivers/hwtracing/coresight/coresight-tmc-etr.c | 2 +- > drivers/hwtracing/coresight/coresight-tmc.h | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c > index 766325de0e29..1425ecd1cf78 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c > +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c > @@ -1267,7 +1267,7 @@ alloc_etr_buf(struct tmc_drvdata *drvdata, struct perf_event *event, > * than the size requested via sysfs. > */ > if ((nr_pages << PAGE_SHIFT) > drvdata->size) { > - etr_buf = tmc_alloc_etr_buf(drvdata, (nr_pages << PAGE_SHIFT), > + etr_buf = tmc_alloc_etr_buf(drvdata, ((ssize_t)nr_pages << PAGE_SHIFT), > 0, node, NULL); > if (!IS_ERR(etr_buf)) > goto done; > diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h > index b97da39652d2..0ee48c5ba764 100644 > --- a/drivers/hwtracing/coresight/coresight-tmc.h > +++ b/drivers/hwtracing/coresight/coresight-tmc.h > @@ -325,7 +325,7 @@ ssize_t tmc_sg_table_get_data(struct tmc_sg_table *sg_table, > static inline unsigned long > tmc_sg_table_buf_size(struct tmc_sg_table *sg_table) > { > - return sg_table->data_pages.nr_pages << PAGE_SHIFT; > + return (unsigned long)sg_table->data_pages.nr_pages << PAGE_SHIFT; > } > > struct coresight_device *tmc_etr_get_catu_device(struct tmc_drvdata *drvdata);
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