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SubjectRe: [PATCH] Avoid potential NULL deref in scripts/genksyms/lex.l
On Sun, 24 Jun 2007 23:40:03 +0200 Jesper Juhl <jesper.juhl@gmail.com> wrote:

> strchr() returns NULL in case the string is not found and if that
> happens we risk dereferencing a NULL pointer. It never hurts to
> check for that condition and exit normally with an error rather
> than crashing.
>
> (no, the indentation is not according to CodingStyle, it's simply
> following whatever else is in that file)
>
>
> Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
> ---
>
> scripts/genksyms/lex.l | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/scripts/genksyms/lex.l b/scripts/genksyms/lex.l
> index 5e544a0..28edc0c 100644
> --- a/scripts/genksyms/lex.l
> +++ b/scripts/genksyms/lex.l
> @@ -154,6 +154,8 @@ repeat:
>
> file = strchr(yytext, '\"')+1;
> e = strchr(file, '\"');

If `file' can be null we'd have oopsed here.

> + if (!file || !e)
> + exit(1);
> *e = '\0';
> cur_filename = memcpy(xmalloc(e-file+1), file, e-file+1);
> cur_line = atoi(yytext+2);

I don't think the bug which you're fixing can occur:

^#[ \t]+{INT}[ \t]+\"[^\"\n]+\".*\n return FILENAME;

has anyone reported crashes in there?
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