[PATCH v3] acpi: nfit: vmalloc-out-of-bounds Read in acpi_nfit_ctl

Suraj Sonawane
2024-11-13T12:52:10Z

Fix an issue detected by syzbot with KASAN:

BUG: KASAN: vmalloc-out-of-bounds in cmd_to_func drivers/acpi/nfit/
core.c:416 [inline]
BUG: KASAN: vmalloc-out-of-bounds in acpi_nfit_ctl+0x20e8/0x24a0
drivers/acpi/nfit/core.c:459

The issue occurs in cmd_to_func when the call_pkg->nd_reserved2
array is accessed without verifying that call_pkg points to a buffer
that is appropriately sized as a struct nd_cmd_pkg. This can lead
to out-of-bounds access and undefined behavior if the buffer does not
have sufficient space.

To address this, a check was added in acpi_nfit_ctl() to ensure that
buf is not NULL and that buf_len is greater than sizeof(*call_pkg)
before casting buf to struct nd_cmd_pkg *. This ensures safe access
to the members of call_pkg, including the nd_reserved2 array.

Reported-by: syzbot+7534f060ebda6b8b51b3@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=7534f060ebda6b8b51b3
Tested-by: syzbot+7534f060ebda6b8b51b3@syzkaller.appspotmail.com
Fixes: ebe9f6f19d80 ("acpi/nfit: Fix bus command validation")
Signed-off-by: Suraj Sonawane <surajsonawane0215@gmail.com>
---
V1: https://lore.kernel.org/lkml/20241111080429.9861-1-surajsonawane0215@gmail.com/
V2: Initialized `out_obj` to `NULL` in `acpi_nfit_ctl()` to prevent
potential uninitialized variable usage if condition is true.
V3: Changed the condition to if (!buf || buf_len < sizeof(*call_pkg))
and updated the Fixes tag to reference the correct commit.

drivers/acpi/nfit/core.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 5429ec9ef..eb5349606 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -439,7 +439,7 @@ int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
{
struct acpi_nfit_desc *acpi_desc = to_acpi_desc(nd_desc);
struct nfit_mem *nfit_mem = nvdimm_provider_data(nvdimm);
- union acpi_object in_obj, in_buf, *out_obj;
+ union acpi_object in_obj, in_buf, *out_obj = NULL;
const struct nd_cmd_desc *desc = NULL;
struct device *dev = acpi_desc->dev;
struct nd_cmd_pkg *call_pkg = NULL;
@@ -454,8 +454,14 @@ int acpi_nfit_ctl(struct nvdimm_bus_descriptor *nd_desc, struct nvdimm *nvdimm,
if (cmd_rc)
*cmd_rc = -EINVAL;

- if (cmd == ND_CMD_CALL)
- call_pkg = buf;
+ if (cmd == ND_CMD_CALL) {
+ if (!buf || buf_len < sizeof(*call_pkg)) {
+ rc = -EINVAL;
+ goto out;
+ }
+ call_pkg = (struct nd_cmd_pkg *)buf;
+ }
+
func = cmd_to_func(nfit_mem, cmd, call_pkg, &family);
if (func < 0)
return func;
--
2.34.1