From: Kees Cook Date: Tue, 20 May 2025 16:31:35 +0000 (-0700) Subject: Bluetooth: btintel: Check dsbr size from EFI variable X-Git-Tag: v6.16-rc1~132^2~47^2 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=3aa1dc3c9060e335e82e9c182bf3d1db29220b1b;p=linux-block.git Bluetooth: btintel: Check dsbr size from EFI variable Since the size of struct btintel_dsbr is already known, we can just start there instead of querying the EFI variable size. If the final result doesn't match what we expect also fail. This fixes a stack buffer overflow when the EFI variable is larger than struct btintel_dsbr. Reported-by: zepta Closes: https://lore.kernel.org/all/CAPBS6KoaWV9=dtjTESZiU6KK__OZX0KpDk-=JEH8jCHFLUYv3Q@mail.gmail.com Fixes: eb9e749c0182 ("Bluetooth: btintel: Allow configuring drive strength of BRI") Signed-off-by: Kees Cook Signed-off-by: Luiz Augusto von Dentz --- diff --git a/drivers/bluetooth/btintel.c b/drivers/bluetooth/btintel.c index ae92490d0c78..55cc1652bfe4 100644 --- a/drivers/bluetooth/btintel.c +++ b/drivers/bluetooth/btintel.c @@ -2719,7 +2719,7 @@ static int btintel_uefi_get_dsbr(u32 *dsbr_var) } __packed data; efi_status_t status; - unsigned long data_size = 0; + unsigned long data_size = sizeof(data); efi_guid_t guid = EFI_GUID(0xe65d8884, 0xd4af, 0x4b20, 0x8d, 0x03, 0x77, 0x2e, 0xcc, 0x3d, 0xa5, 0x31); @@ -2729,16 +2729,10 @@ static int btintel_uefi_get_dsbr(u32 *dsbr_var) if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) return -EOPNOTSUPP; - status = efi.get_variable(BTINTEL_EFI_DSBR, &guid, NULL, &data_size, - NULL); - - if (status != EFI_BUFFER_TOO_SMALL || !data_size) - return -EIO; - status = efi.get_variable(BTINTEL_EFI_DSBR, &guid, NULL, &data_size, &data); - if (status != EFI_SUCCESS) + if (status != EFI_SUCCESS || data_size != sizeof(data)) return -ENXIO; *dsbr_var = data.dsbr;