bug: disk/mkfs crashes in libdisk when given a directory as a protofile

bug: disk/mkfs crashes in libdisk when given a directory as a protofile

[Nick Owens]

the following command will crash:

disk/mkfs -a -o .

with a null pointer dereference in libdisk, in the proto file parser.

obviously it is wrong to pass a directory as a protofile to mkfs, but
it was an accident on my part.

Re: bug: disk/mkfs crashes in libdisk when given a directory as a protofile

[Nick Owens]

[-- Attachment #1: Type: text/plain, Size: 436 bytes --]

this bug was introduced in revision c7027d120f0c. attached is a diff
which prevents this crash in libdisk. any thoughts?
On Tue, Sep 18, 2018 at 8:42 PM Nick Owens <mischief@offblast.org> wrote:
>
> the following command will crash:
>
> disk/mkfs -a -o .
>
> with a null pointer dereference in libdisk, in the proto file parser.
>
> obviously it is wrong to pass a directory as a protofile to mkfs, but
> it was an accident on my part.

[-- Attachment #2: libdisk.patch --]
[-- Type: text/x-patch, Size: 338 bytes --]

diff --git a/sys/src/libdisk/proto.c b/sys/src/libdisk/proto.c
--- a/sys/src/libdisk/proto.c
+++ b/sys/src/libdisk/proto.c
@@ -537,7 +537,10 @@ loop:
 		goto loop;
 	p--;
 	popopt(mkaux);
-	*strchr(p, '\n') = 0;
+	s = strchr(p, '\n');
+	if(s == nil)
+		return nil;
+	*s = 0;
 	if(s = strchr(p, '=')){
 		*s++ = 0;
 		setopt(mkaux, p, s);