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Re: [PATCH] zram: fix possible use after free in zcomp_create()

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On (09/07/15 11:33), Luis Henriques wrote:
> zcomp_create() verifies the success of zcomp_strm_{multi,siggle}_create()
> through comp->stream, which can potentially be pointing to memory that was
> freed if these functions returned an error.
> 

good catch.

we probably better start checking the zcomp_strm_multi_create()/
zcomp_strm_single_create() status in zcomp_create(); that's much
more obvious and that's why we return it in the first place.

what do you think?

---

 drivers/block/zram/zcomp.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
index 3456d5a..16bbc8c 100644
--- a/drivers/block/zram/zcomp.c
+++ b/drivers/block/zram/zcomp.c
@@ -360,6 +360,7 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
 {
 	struct zcomp *comp;
 	struct zcomp_backend *backend;
+	int ret;
 
 	backend = find_backend(compress);
 	if (!backend)
@@ -371,10 +372,10 @@ struct zcomp *zcomp_create(const char *compress, int max_strm)
 
 	comp->backend = backend;
 	if (max_strm > 1)
-		zcomp_strm_multi_create(comp, max_strm);
+		ret = zcomp_strm_multi_create(comp, max_strm);
 	else
-		zcomp_strm_single_create(comp);
-	if (!comp->stream) {
+		ret = zcomp_strm_single_create(comp);
+	if (ret != 0) {
 		kfree(comp);
 		return ERR_PTR(-ENOMEM);
 	}

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[PATCH] zram: fix possible use after free in zcomp_create() Luis Henriques <luis.henriques@canonical.com> - 2015-09-07 12:40 +0200
  Re: [PATCH] zram: fix possible use after free in zcomp_create() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-09-07 13:20 +0200
    Re: [PATCH] zram: fix possible use after free in zcomp_create() Luis Henriques <luis.henriques@canonical.com> - 2015-09-07 15:00 +0200
      Re: [PATCH] zram: fix possible use after free in zcomp_create() Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2015-09-07 15:40 +0200
        Re: [PATCH] zram: fix possible use after free in zcomp_create() Luis Henriques <luis.henriques@canonical.com> - 2015-09-07 16:20 +0200
        [PATCH v2] zram: fix possible use after free in zcomp_create() Luis Henriques <luis.henriques@canonical.com> - 2015-09-07 16:20 +0200
          Re: [PATCH v2] zram: fix possible use after free in zcomp_create() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-09-08 02:00 +0200
          Re: [PATCH v2] zram: fix possible use after free in zcomp_create() Minchan Kim <minchan@kernel.org> - 2015-09-08 03:10 +0200
            Re: [PATCH v2] zram: fix possible use after free in zcomp_create() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-09-08 03:30 +0200
              Re: [PATCH v2] zram: fix possible use after free in zcomp_create() Minchan Kim <minchan@kernel.org> - 2015-09-08 03:40 +0200
                [PATCH v3] zram: fix possible use after free in zcomp_create() Luis Henriques <luis.henriques@canonical.com> - 2015-09-08 11:40 +0200
                Re: [PATCH v3] zram: fix possible use after free in zcomp_create() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-09-08 12:00 +0200
                Re: [PATCH v3] zram: fix possible use after free in zcomp_create() Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2015-09-08 12:30 +0200
                Re: [PATCH v3] zram: fix possible use after free in zcomp_create() Minchan Kim <minchan@kernel.org> - 2015-09-08 15:40 +0200

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