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,