[PATCH 5.8 261/633] misc: mic: scif: Fix error handling path

Greg Kroah-Hartman
2020-10-27T15:02:59Z

From: Souptick Joarder <jrdr.linux@gmail.com>

[ Upstream commit a81072a9c0ae734b7889929b0bc070fe3f353f0e ]

Inside __scif_pin_pages(), when map_flags != SCIF_MAP_KERNEL it
will call pin_user_pages_fast() to map nr_pages. However,
pin_user_pages_fast() might fail with a return value -ERRNO.

The return value is stored in pinned_pages->nr_pages. which in
turn is passed to unpin_user_pages(), which expects
pinned_pages->nr_pages >=0, else disaster.

Fix this by assigning pinned_pages->nr_pages to 0 if
pin_user_pages_fast() returns -ERRNO.

Fixes: ba612aa8b487 ("misc: mic: SCIF memory registration and unregistration")
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Link: https://lore.kernel.org/r/1600570295-29546-1-git-send-email-jrdr.linux@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/misc/mic/scif/scif_rma.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/mic/scif/scif_rma.c b/drivers/misc/mic/scif/scif_rma.c
index 406cd5abfa726..56c784699eb8e 100644
--- a/drivers/misc/mic/scif/scif_rma.c
+++ b/drivers/misc/mic/scif/scif_rma.c
@@ -1384,6 +1384,8 @@ int __scif_pin_pages(void *addr, size_t len, int *out_prot,
(prot & SCIF_PROT_WRITE) ? FOLL_WRITE : 0,
pinned_pages->pages);
if (nr_pages != pinned_pages->nr_pages) {
+ if (pinned_pages->nr_pages < 0)
+ pinned_pages->nr_pages = 0;
if (try_upgrade) {
if (ulimit)
__scif_dec_pinned_vm_lock(mm, nr_pages);
@@ -1400,7 +1402,6 @@ int __scif_pin_pages(void *addr, size_t len, int *out_prot,

if (pinned_pages->nr_pages < nr_pages) {
err = -EFAULT;
- pinned_pages->nr_pages = nr_pages;
goto dec_pinned;
}

@@ -1413,7 +1414,6 @@ int __scif_pin_pages(void *addr, size_t len, int *out_prot,
__scif_dec_pinned_vm_lock(mm, nr_pages);
/* Something went wrong! Rollback */
error_unmap:
- pinned_pages->nr_pages = nr_pages;
scif_destroy_pinned_pages(pinned_pages);
*pages = NULL;
dev_dbg(scif_info.mdev.this_device,
--
2.25.1