This is a note to let you know that I've just added the patch titled
RDMA/core: Fix ib block iterator counter overflow
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rdma-core-fix-ib-block-iterator-counter-overflow.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit f88797fad89eb2e494ddea953f3c2193fd4def21
Author: Yonatan Nachum <ynachum@xxxxxxxxxx>
Date: Mon Jan 9 13:37:11 2023 +0000
RDMA/core: Fix ib block iterator counter overflow
[ Upstream commit 0afec5e9cea732cb47014655685a2a47fb180c31 ]
When registering a new DMA MR after selecting the best aligned page size
for it, we iterate over the given sglist to split each entry to smaller,
aligned to the selected page size, DMA blocks.
In given circumstances where the sg entry and page size fit certain
sizes and the sg entry is not aligned to the selected page size, the
total size of the aligned pages we need to cover the sg entry is >= 4GB.
Under this circumstances, while iterating page aligned blocks, the
counter responsible for counting how much we advanced from the start of
the sg entry is overflowed because its type is u32 and we pass 4GB in
size. This can lead to an infinite loop inside the iterator function
because the overflow prevents the counter to be larger
than the size of the sg entry.
Fix the presented problem by changing the advancement condition to
eliminate overflow.
Backtrace:
[ 192.374329] efa_reg_user_mr_dmabuf
[ 192.376783] efa_register_mr
[ 192.382579] pgsz_bitmap 0xfffff000 rounddown 0x80000000
[ 192.386423] pg_sz [0x80000000] umem_length[0xc0000000]
[ 192.392657] start 0x0 length 0xc0000000 params.page_shift 31 params.page_num 3
[ 192.399559] hp_cnt[3], pages_in_hp[524288]
[ 192.403690] umem->sgt_append.sgt.nents[1]
[ 192.407905] number entries: [1], pg_bit: [31]
[ 192.411397] biter->__sg_nents [1] biter->__sg [0000000008b0c5d8]
[ 192.415601] biter->__sg_advance [665837568] sg_dma_len[3221225472]
[ 192.419823] biter->__sg_nents [1] biter->__sg [0000000008b0c5d8]
[ 192.423976] biter->__sg_advance [2813321216] sg_dma_len[3221225472]
[ 192.428243] biter->__sg_nents [1] biter->__sg [0000000008b0c5d8]
[ 192.432397] biter->__sg_advance [665837568] sg_dma_len[3221225472]
Fixes: a808273a495c ("RDMA/verbs: Add a DMA iterator to return aligned contiguous memory blocks")
Signed-off-by: Yonatan Nachum <ynachum@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230109133711.13678-1-ynachum@xxxxxxxxxx
Signed-off-by: Leon Romanovsky <leon@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/infiniband/core/verbs.c b/drivers/infiniband/core/verbs.c
index 26b021f43ba4..11b1c1603aeb 100644
--- a/drivers/infiniband/core/verbs.c
+++ b/drivers/infiniband/core/verbs.c
@@ -2957,15 +2957,18 @@ EXPORT_SYMBOL(__rdma_block_iter_start);
bool __rdma_block_iter_next(struct ib_block_iter *biter)
{
unsigned int block_offset;
+ unsigned int sg_delta;
if (!biter->__sg_nents || !biter->__sg)
return false;
biter->__dma_addr = sg_dma_address(biter->__sg) + biter->__sg_advance;
block_offset = biter->__dma_addr & (BIT_ULL(biter->__pg_bit) - 1);
- biter->__sg_advance += BIT_ULL(biter->__pg_bit) - block_offset;
+ sg_delta = BIT_ULL(biter->__pg_bit) - block_offset;
- if (biter->__sg_advance >= sg_dma_len(biter->__sg)) {
+ if (sg_dma_len(biter->__sg) - biter->__sg_advance > sg_delta) {
+ biter->__sg_advance += sg_delta;
+ } else {
biter->__sg_advance = 0;
biter->__sg = sg_next(biter->__sg);
biter->__sg_nents--;
