* [PATCH] RDMA/bnxt_re: zero shared page before exposing to userspace
[not found] <2026050945-oversight-carefully-93e0@gregkh>
@ 2026-05-09 8:40 ` pomzm67
2026-05-13 18:51 ` Leon Romanovsky
0 siblings, 1 reply; 2+ messages in thread
From: pomzm67 @ 2026-05-09 8:40 UTC (permalink / raw)
To: security
Cc: selvin.xavier, kalesh-anakkur.purayil, jgg, leon, eddie.wai,
somnath.kotur, sriharsha.basavapatna, devesh.sharma, dledford,
gregkh, linux-rdma, linux-kernel, Lord Ulf Henrik Holmberg
From: Lord Ulf Henrik Holmberg <henrik.holmberg@defensify.se>
bnxt_re_alloc_ucontext() allocates uctx->shpg via
__get_free_page(GFP_KERNEL). The buddy allocator does not zero pages
without __GFP_ZERO, so the page contains stale kernel data from
whatever object most recently freed it.
The page is then mapped into userspace via vm_insert_page() under
BNXT_RE_MMAP_SH_PAGE in bnxt_re_mmap(). The driver only ever writes
4 bytes (a u32 AVID) at offset BNXT_RE_AVID_OFFT (0x10) inside
bnxt_re_create_ah(); the remaining 4092 bytes of the page are exposed
to userspace unsanitised, leaking kernel memory contents.
Any user with access to /dev/infiniband/uverbsX on a host with a
bnxt_re device (typically rdma group membership) can read this data
via a single mmap() at pgoff 0 after IB_USER_VERBS_CMD_GET_CONTEXT.
Other shared pages in the same file already use get_zeroed_page()
correctly:
drivers/infiniband/hw/bnxt_re/ib_verbs.c
srq->uctx_srq_page = (void *)get_zeroed_page(GFP_KERNEL);
cq->uctx_cq_page = (void *)get_zeroed_page(GFP_KERNEL);
uctx->shpg is the only outlier. Bring it in line with the existing
convention by switching to get_zeroed_page().
Fixes: 1ac5a4047975 ("RDMA/bnxt_re: Add bnxt_re RoCE driver")
Signed-off-by: Lord Ulf Henrik Holmberg <henrik.holmberg@defensify.se>
---
drivers/infiniband/hw/bnxt_re/ib_verbs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/infiniband/hw/bnxt_re/ib_verbs.c b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
index 7ed294516b7e..365ec2767d25 100644
--- a/drivers/infiniband/hw/bnxt_re/ib_verbs.c
+++ b/drivers/infiniband/hw/bnxt_re/ib_verbs.c
@@ -4638,7 +4638,7 @@ int bnxt_re_alloc_ucontext(struct ib_ucontext *ctx, struct ib_udata *udata)
uctx->rdev = rdev;
- uctx->shpg = (void *)__get_free_page(GFP_KERNEL);
+ uctx->shpg = (void *)get_zeroed_page(GFP_KERNEL);
if (!uctx->shpg) {
rc = -ENOMEM;
goto fail;
--
2.47.3
^ permalink raw reply related [flat|nested] 2+ messages in thread