[PATCH v2] nss: Get rid of alloca usage in db-XXX

[PATCH v2] nss: Get rid of alloca usage in db-XXX

[Joe Simmons-Talbott]

Replace alloca usage with a scratch_buffer.
---
 nss/nss_db/db-XXX.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/nss/nss_db/db-XXX.c b/nss/nss_db/db-XXX.c
index 0ce730db5a..012446fed8 100644
--- a/nss/nss_db/db-XXX.c
+++ b/nss/nss_db/db-XXX.c
@@ -18,6 +18,7 @@
 
 #include <dlfcn.h>
 #include <fcntl.h>
+#include <scratch_buffer.h>
 #include <stdint.h>
 #include <sys/mman.h>
 #include <libc-lock.h>
@@ -126,6 +127,8 @@ enum nss_status								      \
 			char *buffer, size_t buflen, int *errnop H_ERRNO_PROTO)\
 {									      \
   struct parser_data *data = (void *) buffer;				      \
+  struct scratch_buffer sbuf;						      \
+  scratch_buffer_init (&sbuf);						      \
 									      \
   if (buflen < sizeof *data)						      \
     {									      \
@@ -160,7 +163,14 @@ enum nss_status								      \
   else									      \
     {									      \
       const size_t size = (keysize) + 1;				      \
-      key = alloca (size);						      \
+      if (!scratch_buffer_set_array_size (&sbuf, 1, size))		      \
+	{								      \
+	  *errnop = ENOMEM;						      \
+	  H_ERRNO_SET (NETDB_INTERNAL);					      \
+	  status = NSS_STATUS_TRYAGAIN;					      \
+	  goto out;						      \
+	}								      \
+      key = sbuf.data;							      \
 									      \
       KEYPRINTF keypattern;						      \
     }									      \
@@ -216,6 +226,7 @@ enum nss_status								      \
 									      \
  out:									      \
   internal_endent (&state);						      \
+  scratch_buffer_free (&sbuf);						      \
 									      \
   return status;							      \
 }
-- 
2.39.2

Re: [PATCH v2] nss: Get rid of alloca usage in db-XXX

[Andreas Schwab]

On Sep 27 2023, Joe Simmons-Talbott wrote:

> @@ -160,7 +163,14 @@ enum nss_status								      \
>    else									      \
>      {									      \
>        const size_t size = (keysize) + 1;				      \
> -      key = alloca (size);						      \
> +      if (!scratch_buffer_set_array_size (&sbuf, 1, size))		      \
> +	{								      \
> +	  *errnop = ENOMEM;						      \
> +	  H_ERRNO_SET (NETDB_INTERNAL);					      \
> +	  status = NSS_STATUS_TRYAGAIN;					      \
> +	  goto out;						      \

The backslash is not aligned.  Ok with that change.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

Re: [PATCH v2] nss: Get rid of alloca usage in db-XXX

[Andreas Schwab]

On Sep 27 2023, Joe Simmons-Talbott wrote:

> @@ -160,7 +163,14 @@ enum nss_status								      \
>    else									      \
>      {									      \
>        const size_t size = (keysize) + 1;				      \
> -      key = alloca (size);						      \
> +      if (!scratch_buffer_set_array_size (&sbuf, 1, size))		      \
> +	{								      \
> +	  *errnop = ENOMEM;						      \

One more change: this should be errno, not ENOMEM.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

Re: [PATCH v2] nss: Get rid of alloca usage in db-XXX

[Joe Simmons-Talbott]

On Thu, Sep 28, 2023 at 01:19:30PM +0200, Andreas Schwab wrote:
> On Sep 27 2023, Joe Simmons-Talbott wrote:
> 
> > @@ -160,7 +163,14 @@ enum nss_status								      \
> >    else									      \
> >      {									      \
> >        const size_t size = (keysize) + 1;				      \
> > -      key = alloca (size);						      \
> > +      if (!scratch_buffer_set_array_size (&sbuf, 1, size))		      \
> > +	{								      \
> > +	  *errnop = ENOMEM;						      \
> 
> One more change: this should be errno, not ENOMEM.

Thanks for the review.  I've posted a v3 with both changes.

Thanks,
Joe