| Message ID | 20230326165223.2707557-1-elder@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [net] net: ipa: compute DMA pool size properly | expand |
On 26/03/2023 19:52, Alex Elder wrote: > In gsi_trans_pool_init_dma(), the total size of a pool of memory > used for DMA transactions is calculated. However the calculation is > done incorrectly. > > For 4KB pages, this total size is currently always more than one > page, and as a result, the calculation produces a positive (though > incorrect) total size. The code still works in this case; we just > end up with fewer DMA pool entries than we intended. > > Bjorn Andersson tested booting a kernel with 16KB pages, and hit a > null pointer derereference in sg_alloc_append_table_from_pages(), > descending from gsi_trans_pool_init_dma(). The cause of this was > that a 16KB total size was going to be allocated, and with 16KB > pages the order of that allocation is 0. The total_size calculation > yielded 0, which eventually led to the crash. > > Correcting the total_size calculation fixes the problem. > > Reported-by: <quic_bjorande@quicinc.com> > Tested-by: <quic_bjorande@quicinc.com> > Fixes: 9dd441e4ed57 ("soc: qcom: ipa: GSI transactions") > Signed-off-by: Alex Elder <elder@linaro.org> > --- > drivers/net/ipa/gsi_trans.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c > index 0f52c068c46d6..ee6fb00b71eb6 100644 > --- a/drivers/net/ipa/gsi_trans.c > +++ b/drivers/net/ipa/gsi_trans.c > @@ -156,7 +156,7 @@ int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool, > * gsi_trans_pool_exit_dma() can assume the total allocated > * size is exactly (count * size). > */ > - total_size = get_order(total_size) << PAGE_SHIFT; > + total_size = PAGE_SIZE << get_order(total_size); > > virt = dma_alloc_coherent(dev, total_size, &addr, GFP_KERNEL); > if (!virt) Thanks, Reviewed-by: Mark Bloch <mbloch@nvidia.com>
On Sun, Mar 26, 2023 at 11:52:23AM -0500, Alex Elder wrote: > In gsi_trans_pool_init_dma(), the total size of a pool of memory > used for DMA transactions is calculated. However the calculation is > done incorrectly. > > For 4KB pages, this total size is currently always more than one > page, and as a result, the calculation produces a positive (though > incorrect) total size. The code still works in this case; we just > end up with fewer DMA pool entries than we intended. > > Bjorn Andersson tested booting a kernel with 16KB pages, and hit a > null pointer derereference in sg_alloc_append_table_from_pages(), > descending from gsi_trans_pool_init_dma(). The cause of this was > that a 16KB total size was going to be allocated, and with 16KB > pages the order of that allocation is 0. The total_size calculation > yielded 0, which eventually led to the crash. > > Correcting the total_size calculation fixes the problem. > > Reported-by: <quic_bjorande@quicinc.com> > Tested-by: <quic_bjorande@quicinc.com> It would be nice to add "Bjorn Andersson" to these two. Regards, Bjorn > Fixes: 9dd441e4ed57 ("soc: qcom: ipa: GSI transactions") > Signed-off-by: Alex Elder <elder@linaro.org> > --- > drivers/net/ipa/gsi_trans.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c > index 0f52c068c46d6..ee6fb00b71eb6 100644 > --- a/drivers/net/ipa/gsi_trans.c > +++ b/drivers/net/ipa/gsi_trans.c > @@ -156,7 +156,7 @@ int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool, > * gsi_trans_pool_exit_dma() can assume the total allocated > * size is exactly (count * size). > */ > - total_size = get_order(total_size) << PAGE_SHIFT; > + total_size = PAGE_SIZE << get_order(total_size); > > virt = dma_alloc_coherent(dev, total_size, &addr, GFP_KERNEL); > if (!virt) > -- > 2.34.1 >
diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c index 0f52c068c46d6..ee6fb00b71eb6 100644 --- a/drivers/net/ipa/gsi_trans.c +++ b/drivers/net/ipa/gsi_trans.c @@ -156,7 +156,7 @@ int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool, * gsi_trans_pool_exit_dma() can assume the total allocated * size is exactly (count * size). */ - total_size = get_order(total_size) << PAGE_SHIFT; + total_size = PAGE_SIZE << get_order(total_size); virt = dma_alloc_coherent(dev, total_size, &addr, GFP_KERNEL); if (!virt)