| From 5aa8461d4aaee2eb7b525b5888bf1ac41e16af67 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Mon, 29 Jun 2020 11:37:56 +0200 |
| Subject: scsi: target: tcmu: Fix crash on ARM during cmd completion |
| |
| From: Bodo Stroesser <bstroesser@ts.fujitsu.com> |
| |
| [ Upstream commit 5a0c256d96f020e4771f6fd5524b80f89a2d3132 ] |
| |
| If tcmu_handle_completions() has to process a padding shorter than |
| sizeof(struct tcmu_cmd_entry), the current call to |
| tcmu_flush_dcache_range() with sizeof(struct tcmu_cmd_entry) as length |
| param is wrong and causes crashes on e.g. ARM, because |
| tcmu_flush_dcache_range() in this case calls |
| flush_dcache_page(vmalloc_to_page(start)); with start being an invalid |
| address above the end of the vmalloc'ed area. |
| |
| The fix is to use the minimum of remaining ring space and sizeof(struct |
| tcmu_cmd_entry) as the length param. |
| |
| The patch was tested on kernel 4.19.118. |
| |
| See https://bugzilla.kernel.org/show_bug.cgi?id=208045#c10 |
| |
| Link: https://lore.kernel.org/r/20200629093756.8947-1-bstroesser@ts.fujitsu.com |
| Tested-by: JiangYu <lnsyyj@hotmail.com> |
| Acked-by: Mike Christie <michael.christie@oracle.com> |
| Signed-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com> |
| Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| drivers/target/target_core_user.c | 9 ++++++++- |
| 1 file changed, 8 insertions(+), 1 deletion(-) |
| |
| diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c |
| index 1a83456a65a00..693fbb2858404 100644 |
| --- a/drivers/target/target_core_user.c |
| +++ b/drivers/target/target_core_user.c |
| @@ -666,7 +666,14 @@ static unsigned int tcmu_handle_completions(struct tcmu_dev *udev) |
| struct tcmu_cmd_entry *entry = (void *) mb + CMDR_OFF + udev->cmdr_last_cleaned; |
| struct tcmu_cmd *cmd; |
| |
| - tcmu_flush_dcache_range(entry, sizeof(*entry)); |
| + /* |
| + * Flush max. up to end of cmd ring since current entry might |
| + * be a padding that is shorter than sizeof(*entry) |
| + */ |
| + size_t ring_left = head_to_end(udev->cmdr_last_cleaned, |
| + udev->cmdr_size); |
| + tcmu_flush_dcache_range(entry, ring_left < sizeof(*entry) ? |
| + ring_left : sizeof(*entry)); |
| |
| if (tcmu_hdr_get_op(entry->hdr.len_op) == TCMU_OP_PAD) { |
| UPDATE_HEAD(udev->cmdr_last_cleaned, |
| -- |
| 2.25.1 |
| |
