[PATCH] gdb/debuginfod-support.c: Do not crash if URL list is " "

[PATCH] gdb/debuginfod-support.c: Do not crash if URL list is " "

[Ilya Leoshkevich]

Exit early if find_first_not_of returns npos - passing npos to
substr leads to an exception.
---
 gdb/debuginfod-support.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/gdb/debuginfod-support.c b/gdb/debuginfod-support.c
index 6c2d3fb2951..668c50c405c 100644
--- a/gdb/debuginfod-support.c
+++ b/gdb/debuginfod-support.c
@@ -187,10 +187,13 @@ debuginfod_is_enabled ()
       gdb::string_view url_view (urls);
       while (true)
 	{
-	  url_view = url_view.substr (url_view.find_first_not_of (' '));
+	  size_t off = url_view.find_first_not_of (' ');
+	  if (off == gdb::string_view::npos)
+	    break;
+	  url_view = url_view.substr (off);
 	  if (url_view.empty ())
 	    break;
-	  size_t off = url_view.find_first_of (' ');
+	  off = url_view.find_first_of (' ');
 	  gdb_printf
 	    (_("  <%ps>\n"),
 	     styled_string (file_name_style.style (),
-- 
2.35.1

Re: [PATCH] gdb/debuginfod-support.c: Do not crash if URL list is " "

[Bruno Larsen]

Ilya hello!


On 4/21/22 07:47, Ilya Leoshkevich via Gdb-patches wrote:
> Exit early if find_first_not_of returns npos - passing npos to
> substr leads to an exception.

Thank you for looking at this! A patch exactly like yours has been pushed just 12 hours before you sent this in (https://sourceware.org/pipermail/gdb-patches/2022-April/187688.html)

> ---
>   gdb/debuginfod-support.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/debuginfod-support.c b/gdb/debuginfod-support.c
> index 6c2d3fb2951..668c50c405c 100644
> --- a/gdb/debuginfod-support.c
> +++ b/gdb/debuginfod-support.c
> @@ -187,10 +187,13 @@ debuginfod_is_enabled ()
>         gdb::string_view url_view (urls);
>         while (true)
>   	{
> -	  url_view = url_view.substr (url_view.find_first_not_of (' '));
> +	  size_t off = url_view.find_first_not_of (' ');
> +	  if (off == gdb::string_view::npos)
> +	    break;
> +	  url_view = url_view.substr (off);
>   	  if (url_view.empty ())
>   	    break;
> -	  size_t off = url_view.find_first_of (' ');
> +	  off = url_view.find_first_of (' ');
>   	  gdb_printf
>   	    (_("  <%ps>\n"),
>   	     styled_string (file_name_style.style (),


Cheers!
Bruno Larsen

Re: [PATCH] gdb/debuginfod-support.c: Do not crash if URL list is " "

[Ilya Leoshkevich]

On Thu, 2022-04-21 at 12:47 +0200, Ilya Leoshkevich wrote:
> Exit early if find_first_not_of returns npos - passing npos to
> substr leads to an exception.
> ---
>  gdb/debuginfod-support.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/gdb/debuginfod-support.c b/gdb/debuginfod-support.c
> index 6c2d3fb2951..668c50c405c 100644
> --- a/gdb/debuginfod-support.c
> +++ b/gdb/debuginfod-support.c
> @@ -187,10 +187,13 @@ debuginfod_is_enabled ()
>        gdb::string_view url_view (urls);
>        while (true)
>         {
> -         url_view = url_view.substr (url_view.find_first_not_of ('
> '));
> +         size_t off = url_view.find_first_not_of (' ');
> +         if (off == gdb::string_view::npos)
> +           break;
> +         url_view = url_view.substr (off);
>           if (url_view.empty ())
>             break;
> -         size_t off = url_view.find_first_of (' ');
> +         off = url_view.find_first_of (' ');
>           gdb_printf
>             (_("  <%ps>\n"),
>              styled_string (file_name_style.style (),

Please disregard this patch - I just noticed that this is already fixed
by https://sourceware.org/pipermail/gdb-patches/2022-April/187688.html

Best regards,
Ilya