In case MMIO size is bigger than 4G and peer2peer DMA goes
through host bridge, we trigger a code path that assigns the
total linked IOVA (which is greater than 4G) to mapped_len.
Previously, `mapped_len` was declared as 32-bit `unsigned int`.
When accumulating `size_t` lengths, this leads to a silent wrap-around.
This truncation causes truncated lengths to be passed to functions
like `fill_sg_entry()`.
Fix this by changing `mapped_len` to `size_t` (64-bit). While
at it, fix similar potential overflow issues in `calc_sg_nents`
by using `size_t` for `nents` and checking against `UINT_MAX`
and using `unsigned int` for the loop iterator in `fill_sg_entry`
to match.
Fixes: 3aa31a8bb11e ("dma-buf: provide phys_vec to scatter-gather mapping
routine")
Cc: [email protected]
Cc: [email protected]
Reviewed-by: Pranjal Shrivastava <[email protected]>
Signed-off-by: David Hu <[email protected]>
---
Changes in v4:
- Added WARN_ON_ONCE() to the nents overflow check to prevent silent
failures (Claude Bot).
Changes in v3:
- Removed leftover sentence fragment from the commit message.
- Kept `nents = 0` initialization (previously stated as removed in the
v2 changelog) as it is strictly required for the `+=` accumulation
loop in `calc_sg_nents()`.
Changes in v2:
- Fixed 'IVOA' -> 'IOVA' typo and expanded commit message (Claude Bot).
- Added Reverse Xmas tree formatting (Pranjal).
- Folded in extra bounds checking for calc_sg_nents() (Pranjal).
- Folded in type consistency fix for fill_sg_entry() (Pranjal).
drivers/dma-buf/dma-buf-mapping.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/dma-buf/dma-buf-mapping.c
b/drivers/dma-buf/dma-buf-mapping.c
index 794acff2546a..1aabc0ee70bb 100644
--- a/drivers/dma-buf/dma-buf-mapping.c
+++ b/drivers/dma-buf/dma-buf-mapping.c
@@ -10,7 +10,7 @@ static struct scatterlist *fill_sg_entry(struct scatterlist
*sgl, size_t length,
dma_addr_t addr)
{
unsigned int len, nents;
- int i;
+ unsigned int i;
nents = DIV_ROUND_UP(length, UINT_MAX);
for (i = 0; i < nents; i++) {
@@ -36,7 +36,7 @@ static unsigned int calc_sg_nents(struct dma_iova_state
*state,
struct phys_vec *phys_vec, size_t nr_ranges,
size_t size)
{
- unsigned int nents = 0;
+ size_t nents = 0;
size_t i;
if (!state || !dma_use_iova(state)) {
@@ -51,6 +51,9 @@ static unsigned int calc_sg_nents(struct dma_iova_state
*state,
nents = DIV_ROUND_UP(size, UINT_MAX);
}
+ if (WARN_ON_ONCE(nents > UINT_MAX))
+ return 0;
+
return nents;
}
@@ -95,9 +98,10 @@ struct sg_table *dma_buf_phys_vec_to_sgt(struct
dma_buf_attachment *attach,
size_t nr_ranges, size_t size,
enum dma_data_direction dir)
{
- unsigned int nents, mapped_len = 0;
struct dma_buf_dma *dma;
struct scatterlist *sgl;
+ size_t mapped_len = 0;
+ unsigned int nents;
dma_addr_t addr;
size_t i;
int ret;
--
2.54.0.929.g9b7fa37559-goog
