[PATCH] Bluetooth: vhci: Avoid needless snprintf() calls

Kees Cook
2025-04-15T16:15:25Z

Avoid double-copying of string literals. Use a "const char *" for each
string instead of copying from .rodata into stack and then into the skb.
We can go directly from .rodata to the skb.

This also works around a Clang bug (that has since been fixed[1]).

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202401250927.1poZERd6-lkp@intel.com/
Fixes: ab4e4380d4e1 ("Bluetooth: Add vhci devcoredump support")
Link: https://github.com/llvm/llvm-project/commit/ea2e66aa8b6e363b89df66dc44275a0d7ecd70ce [1]
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
---
Cc: Marcel Holtmann <marcel@holtmann.org>
Cc: Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: linux-bluetooth@vger.kernel.org
---
drivers/bluetooth/hci_vhci.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/bluetooth/hci_vhci.c b/drivers/bluetooth/hci_vhci.c
index 7651321d351c..9ac22e4a070b 100644
--- a/drivers/bluetooth/hci_vhci.c
+++ b/drivers/bluetooth/hci_vhci.c
@@ -289,18 +289,18 @@ static void vhci_coredump(struct hci_dev *hdev)

static void vhci_coredump_hdr(struct hci_dev *hdev, struct sk_buff *skb)
{
- char buf[80];
+ const char *buf;

- snprintf(buf, sizeof(buf), "Controller Name: vhci_ctrl\n");
+ buf = "Controller Name: vhci_ctrl\n";
skb_put_data(skb, buf, strlen(buf));

- snprintf(buf, sizeof(buf), "Firmware Version: vhci_fw\n");
+ buf = "Firmware Version: vhci_fw\n";
skb_put_data(skb, buf, strlen(buf));

- snprintf(buf, sizeof(buf), "Driver: vhci_drv\n");
+ buf = "Driver: vhci_drv\n";
skb_put_data(skb, buf, strlen(buf));

- snprintf(buf, sizeof(buf), "Vendor: vhci\n");
+ buf = "Vendor: vhci\n";
skb_put_data(skb, buf, strlen(buf));
}

--
2.34.1