Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1451722

Re: lib/mpi: BUG: sleeping function called from invalid context on next-20160726

Show all headers | View raw

On Wed, Jul 27, 2016 at 11:05:05PM +0200, Nicolai Stange wrote:
> 
> with linux-next-20160726, I get this:
> 
>  BUG: sleeping function called from invalid context at /mnt/scratch/nic/linux-next/mm/slab.h:388

Does this patch help?
 
> I would have sent a patch, but there is another point which puzzles me
> in mpi_read_raw_from_sgl():
> 
>   [...]
>   const u8 *buff;
>   [...]
>   sg_miter_start(&miter, sgl, ents, SG_MITER_ATOMIC | SG_MITER_FROM_SG);
> 
>   lzeros = 0;
>   len = 0;
>   while (nbytes > 0) {
>   	while (len && !*buff) {
>   		lzeros++;
>   		len--;
>   		buff++;
>   	}
> 
> 
> Thus, buff isn't initialized before its first use? Or am I misreading
> something here?

On the first entry len is zero therefore we will go to the end of the
loop and initialise buff.  Anyway, it will no longer be as confusing
with this patch applied.

Thanks,

---8<---
Subject: lib/mpi: Fix SG miter leak

In mpi_read_raw_from_sgl we may leak the SG miter resouces after
reading the leading zeroes.  This patch fixes this by stopping the
iteration once the leading zeroes have been read.

Fixes: 127827b9c295 ("lib/mpi: Do not do sg_virt")
Reported-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c
index c6272ae..5a0f75a 100644
--- a/lib/mpi/mpicoder.c
+++ b/lib/mpi/mpicoder.c
@@ -363,6 +363,9 @@ MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes)
 		lzeros = 0;
 	}
 
+	miter.consumed = lzeros;
+	sg_miter_stop(&miter);
+
 	nbytes -= lzeros;
 	nbits = nbytes * 8;
 	if (nbits > MAX_EXTERN_MPI_BITS) {
@@ -390,7 +393,10 @@ MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes)
 	z = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB;
 	z %= BYTES_PER_MPI_LIMB;
 
-	for (;;) {
+	while (sg_miter_next(&miter)) {
+		buff = miter.addr;
+		len = miter.length;
+
 		for (x = 0; x < len; x++) {
 			a <<= 8;
 			a |= *buff++;
@@ -400,12 +406,6 @@ MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes)
 			}
 		}
 		z += x;
-
-		if (!sg_miter_next(&miter))
-			break;
-
-		buff = miter.addr;
-		len = miter.length;
 	}
 
 	return val;
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

lib/mpi: BUG: sleeping function called from invalid context on next-20160726 Nicolai Stange <nicstange@gmail.com> - 2016-07-27 23:10 +0200
  Re: lib/mpi: BUG: sleeping function called from invalid context on  next-20160726 Herbert Xu <herbert@gondor.apana.org.au> - 2016-07-28 07:30 +0200
    Re: lib/mpi: BUG: sleeping function called from invalid context on next-20160726 Nicolai Stange <nicstange@gmail.com> - 2016-07-28 09:50 +0200

csiph-web