VenHw and VenMedia device path nodes may carry vendor defined data of arbitrary length. When converting a device path node to text ensure that we do not overrun our internal buffer.
In our implementation of EFI_DEVICE_PATH_TO_TEXT_PROTOCOL.ConvertDevicePathToText() we could first determine the output length and then allocate buffers but that would nearly double the code size. Therefore keep the preallocated buffers and truncate excessive device paths instead. Signed-off-by: Heinrich Schuchardt <[email protected]> --- lib/efi_loader/efi_device_path_to_text.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/lib/efi_loader/efi_device_path_to_text.c b/lib/efi_loader/efi_device_path_to_text.c index 81b8ac23ba..ba1ad33459 100644 --- a/lib/efi_loader/efi_device_path_to_text.c +++ b/lib/efi_loader/efi_device_path_to_text.c @@ -67,7 +67,8 @@ static char *dp_hardware(char *s, struct efi_device_path *dp) s += sprintf(s, "VenHw(%pUl", &vdp->guid); n = (int)vdp->dp.length - sizeof(struct efi_device_path_vendor); - if (n > 0) { + /* Node must fit into MAX_NODE_LEN) */ + if (n > 0 && n < MAX_NODE_LEN / 2 - 22) { s += sprintf(s, ","); for (i = 0; i < n; ++i) s += sprintf(s, "%02x", vdp->vendor_data[i]); @@ -251,7 +252,8 @@ static char *dp_media(char *s, struct efi_device_path *dp) s += sprintf(s, "VenMedia(%pUl", &vdp->guid); n = (int)vdp->dp.length - sizeof(struct efi_device_path_vendor); - if (n > 0) { + /* Node must fit into MAX_NODE_LEN) */ + if (n > 0 && n < MAX_NODE_LEN / 2 - 24) { s += sprintf(s, ","); for (i = 0; i < n; ++i) s += sprintf(s, "%02x", vdp->vendor_data[i]); -- 2.30.0
