get_supported_features() assigns entries->num_features only after the
memcpy() loop that fills entries->ent[] has already run. Since ent[]
is __counted_by(num_features), the compiler's bounds instrumentation
sees a 0-length array during that loop and FORTIFY_SOURCE trips on
the memcpy. Set @num_features right after allocation, before any
write into ent[], so the bound is correct for the whole lifetime of
the array.
This was found via a fortify panic:
memcpy: detected buffer overflow: 384 byte write of buffer size 0
WARNING: lib/string_helpers.c:1035 at __fortify_report+0x54/0xa0
kernel BUG at lib/string_helpers.c:1043!
Call trace:
__fortify_panic+0x10/0x18
get_supported_features.isra.0+0x4a0/0x4d0 [cxl_core]
devm_cxl_setup_features+0x84/0x120 [cxl_core]
cxl_pci_probe+0x254/0x5e0 [cxl_pci]
Same class of bug, same fix shape as commit 6c9d2e87df40
("cxl/fwctl: Fix __fortify_panic"), which fixed the analogous issue
in cxlctl_get_supported_features() but missed this one.
Fixes: f0e6a2329bf9 ("cxl: Add Get Supported Features command for kernel usage")
Signed-off-by: Ashok Raj <[email protected]>
---
RESEND: Dropped the mailing lists (linux-cxl, linux-kernel) from Cc
by mistake on the first send. Resending with proper Cc.
drivers/cxl/core/features.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/cxl/core/features.c b/drivers/cxl/core/features.c
index ba6d2a5acb74..754fe5eb4b76 100644
--- a/drivers/cxl/core/features.c
+++ b/drivers/cxl/core/features.c
@@ -97,6 +97,7 @@ get_supported_features(struct cxl_features_state *cxlfs)
kvmalloc_flex(*entries, ent, count);
if (!entries)
return NULL;
+ entries->num_features = count;
struct cxl_mbox_get_sup_feats_out *mbox_out __free(kvfree) =
kvmalloc(cxl_mbox->payload_size, GFP_KERNEL);
@@ -174,7 +175,6 @@ get_supported_features(struct cxl_features_state *cxlfs)
start += num_entries;
} while (remain_feats);
- entries->num_features = count;
entries->num_user_features = user_feats;
return no_free_ptr(entries);
--
2.43.0
