[RFC PATCH] scsi: ses: Fix out-of-bound write at ses_enclosure_data_process()
From: Tianchen Ding
Date: Thu Apr 14 2022 - 23:23:27 EST
Our modified KFENCE reported a memory corruption:
[ 52.584914] BUG: KFENCE: memory corruption in ses_enclosure_data_process+0x24b/0x310 [ses]
[ 52.584917] Corrupted memory at 0xffff88982de06ff0 [ 0x00 . . . . . . . . . . . . . . . ] (in kfence-#1624698):
[ 52.607212] ses_enclosure_data_process+0x24b/0x310 [ses]
[ 52.607215] ses_intf_add+0x444/0x542 [ses]
[ 52.621369] class_interface_register+0x110/0x120
[ 52.621373] ses_init+0x13/0x1000 [ses]
[ 52.621377] do_one_initcall+0x41/0x1c0
[ 52.621380] do_init_module+0x5c/0x260
[ 52.621382] __do_sys_finit_module+0xb1/0x110
[ 52.621386] do_syscall_64+0x2d/0x40
[ 52.621388] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 52.621393] kfence-#1624698 [0xffff88982de06fc0-0xffff88982de06fe0, size=33, cache=kmalloc-64] allocated by task 1033:
[ 52.670344] ses_enclosure_data_process+0x2ae/0x310 [ses]
[ 52.670347] ses_intf_add+0x444/0x542 [ses]
[ 52.670353] class_interface_register+0x110/0x120
[ 52.688165] ses_init+0x13/0x1000 [ses]
[ 52.688169] do_one_initcall+0x41/0x1c0
[ 52.688172] do_init_module+0x5c/0x260
[ 52.688174] __do_sys_finit_module+0xb1/0x110
[ 52.688177] do_syscall_64+0x2d/0x40
[ 52.688179] entry_SYSCALL_64_after_hwframe+0x44/0xa9
This is because we check desc_ptr >= buf + page7_len first but then
write '\0' to desc_ptr[len+4], while this address may be out of bound.
Fixes: 21fab1d0595e ("[SCSI] ses: update enclosure data on hot add")
Signed-off-by: Tianchen Ding <dtcccc@xxxxxxxxxxxxxxxxx>
---
drivers/scsi/ses.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/scsi/ses.c b/drivers/scsi/ses.c
index 0a1734f34587..06b991e27c84 100644
--- a/drivers/scsi/ses.c
+++ b/drivers/scsi/ses.c
@@ -559,11 +559,11 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
struct enclosure_component *ecomp;
if (desc_ptr) {
- if (desc_ptr >= buf + page7_len) {
+ len = (desc_ptr[2] << 8) + desc_ptr[3];
+ desc_ptr += 4;
+ if (desc_ptr + len > buf + page7_len) {
desc_ptr = NULL;
} else {
- len = (desc_ptr[2] << 8) + desc_ptr[3];
- desc_ptr += 4;
/* Add trailing zero - pushes into
* reserved space */
desc_ptr[len] = '\0';
--
2.33.0