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dma-mapping fixes for Linux 6.19

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Two minor fixes for DMA-mapping subsystem:
 - check for the rare case of the allocation failure of the global CMA pool
   (Shanker Donthineni)
 - avoid perf buffer overflow when tracing large scatter-gather lists
   (Deepanshu Kartikey)
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Merge tag 'dma-mapping-6.19-2026-02-06' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux

Pull dma-mapping fixes from Marek Szyprowski:
 "Two minor fixes for the DMA-mapping subsystem:

   - check for the rare case of the allocation failure of the global CMA
     pool (Shanker Donthineni)

   - avoid perf buffer overflow when tracing large scatter-gather lists
     (Deepanshu Kartikey)"

* tag 'dma-mapping-6.19-2026-02-06' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
  dma: contiguous: Check return value of dma_contiguous_reserve_area()
  tracing/dma: Cap dma_map_sg tracepoint arrays to prevent buffer overflow
This commit is contained in:
Linus Torvalds 2026-02-06 10:27:42 -08:00
commit 23b0d2f7c2
2 changed files with 25 additions and 10 deletions
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25
include/trace/events/dma.h
View file

@ -275,6 +275,8 @@ TRACE_EVENT(dma_free_sgt,
sizeof(u64), sizeof(u64)))
);
#define DMA_TRACE_MAX_ENTRIES 128
TRACE_EVENT(dma_map_sg,
TP_PROTO(struct device *dev, struct scatterlist *sgl, int nents,
int ents, enum dma_data_direction dir, unsigned long attrs),
@ -282,9 +284,12 @@ TRACE_EVENT(dma_map_sg,
TP_STRUCT__entry(
__string(device, dev_name(dev))
__dynamic_array(u64, phys_addrs, nents)
__dynamic_array(u64, dma_addrs, ents)
__dynamic_array(unsigned int, lengths, ents)
__field(int, full_nents)
__field(int, full_ents)
__field(bool, truncated)
__dynamic_array(u64, phys_addrs, min(nents, DMA_TRACE_MAX_ENTRIES))
__dynamic_array(u64, dma_addrs, min(ents, DMA_TRACE_MAX_ENTRIES))
__dynamic_array(unsigned int, lengths, min(ents, DMA_TRACE_MAX_ENTRIES))
__field(enum dma_data_direction, dir)
__field(unsigned long, attrs)
),
@ -292,11 +297,16 @@ TRACE_EVENT(dma_map_sg,
TP_fast_assign(
struct scatterlist *sg;
int i;
int traced_nents = min_t(int, nents, DMA_TRACE_MAX_ENTRIES);
int traced_ents = min_t(int, ents, DMA_TRACE_MAX_ENTRIES);
__assign_str(device);
for_each_sg(sgl, sg, nents, i)
__entry->full_nents = nents;
__entry->full_ents = ents;
__entry->truncated = (nents > DMA_TRACE_MAX_ENTRIES) || (ents > DMA_TRACE_MAX_ENTRIES);
for_each_sg(sgl, sg, traced_nents, i)
((u64 *)__get_dynamic_array(phys_addrs))[i] = sg_phys(sg);
for_each_sg(sgl, sg, ents, i) {
for_each_sg(sgl, sg, traced_ents, i) {
((u64 *)__get_dynamic_array(dma_addrs))[i] =
sg_dma_address(sg);
((unsigned int *)__get_dynamic_array(lengths))[i] =
@ -306,9 +316,12 @@ TRACE_EVENT(dma_map_sg,
__entry->attrs = attrs;
),
TP_printk("%s dir=%s dma_addrs=%s sizes=%s phys_addrs=%s attrs=%s",
TP_printk("%s dir=%s nents=%d/%d ents=%d/%d%s dma_addrs=%s sizes=%s phys_addrs=%s attrs=%s",
__get_str(device),
decode_dma_data_direction(__entry->dir),
min_t(int, __entry->full_nents, DMA_TRACE_MAX_ENTRIES), __entry->full_nents,
min_t(int, __entry->full_ents, DMA_TRACE_MAX_ENTRIES), __entry->full_ents,
__entry->truncated ? " [TRUNCATED]" : "",
__print_array(__get_dynamic_array(dma_addrs),
__get_dynamic_array_len(dma_addrs) /
sizeof(u64), sizeof(u64)),

10
kernel/dma/contiguous.c
View file

@ -257,10 +257,12 @@ void __init dma_contiguous_reserve(phys_addr_t limit)
pr_debug("%s: reserving %ld MiB for global area\n", __func__,
(unsigned long)selected_size / SZ_1M);
dma_contiguous_reserve_area(selected_size, selected_base,
selected_limit,
&dma_contiguous_default_area,
fixed);
ret = dma_contiguous_reserve_area(selected_size, selected_base,
selected_limit,
&dma_contiguous_default_area,
fixed);
if (ret)
return;
ret = dma_heap_cma_register_heap(dma_contiguous_default_area);
if (ret)