Re: [PATCH] fsl-edma: tracing: no ptr dereference during log output
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2026-06-30 20:05:53
Also in:
dmaengine, imx, lkml
On Tue, 30 Jun 2026 22:00:11 +0200 Martin Kaiser [off-list ref] wrote:
The fsl edma events store a pointer to a struct fsl_edma_engine in the ringbuffer and dereference it when a log entry is printed. At this time, the pointer may no longer be valid.
Nice catch.
Event injection can be used to trigger a crash: $ cd /sys/kernel/tracing $ echo 'value = 0' > events/fsl_edma/edma_writeb/inject $ cat trace The log output needs only edma->membase. Add a membase field at the end of the event and use the new field for log output. Keep the existing fields for backward compatibility.
Cc: stable@vger.kernel.org
Fixes: 11102d0c343b ("dmaengine: fsl-edma: add trace event support")
Signed-off-by: Martin Kaiser <redacted>Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
quoted hunk ↗ jump to hunk
--- drivers/dma/fsl-edma-trace.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)diff --git a/drivers/dma/fsl-edma-trace.h b/drivers/dma/fsl-edma-trace.h index d3541301a247..45d964a3726d 100644 --- a/drivers/dma/fsl-edma-trace.h +++ b/drivers/dma/fsl-edma-trace.h@@ -19,14 +19,16 @@ DECLARE_EVENT_CLASS(edma_log_io, __field(struct fsl_edma_engine *, edma) __field(void __iomem *, addr) __field(u32, value) + __field(void __iomem *, membase) ), TP_fast_assign( __entry->edma = edma; __entry->addr = addr; __entry->value = value; + __entry->membase = edma->membase; ), TP_printk("offset %08x: value %08x", - (u32)(__entry->addr - __entry->edma->membase), __entry->value) + (u32)(__entry->addr - __entry->membase), __entry->value)
Hmm, I think I should update the TP_printk checks at boot to cover this too. -- Steve
); DEFINE_EVENT(edma_log_io, edma_readl,