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authorBodo Stroesser <bstroesser@ts.fujitsu.com>2020-06-29 11:37:56 +0200
committerMartin K. Petersen <martin.petersen@oracle.com>2020-06-29 21:44:57 -0400
commit5a0c256d96f020e4771f6fd5524b80f89a2d3132 (patch)
tree084dca3414068ad8d4794286eb5e21d3113bb983 /drivers/target
parentb7a80dac0f1f16ca5714b89ace8a3fc079686875 (diff)
scsi: target: tcmu: Fix crash on ARM during cmd completion
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>
Diffstat (limited to 'drivers/target')
-rw-r--r--drivers/target/target_core_user.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 3885ca532f8f..366878b0b2fd 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -1221,7 +1221,14 @@ static unsigned int tcmu_handle_completions(struct tcmu_dev *udev)
struct tcmu_cmd_entry *entry = (void *) mb + CMDR_OFF + udev->cmdr_last_cleaned;
- 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,