| From 3aaf14da807a4e9931a37f21e4251abb8a67021b Mon Sep 17 00:00:00 2001 |
| From: Luis Henriques <luis.henriques@canonical.com> |
| Date: Thu, 17 Sep 2015 16:01:40 -0700 |
| Subject: zram: fix possible use after free in zcomp_create() |
| |
| From: Luis Henriques <luis.henriques@canonical.com> |
| |
| commit 3aaf14da807a4e9931a37f21e4251abb8a67021b upstream. |
| |
| zcomp_create() verifies the success of zcomp_strm_{multi,single}_create() |
| through comp->stream, which can potentially be pointing to memory that |
| was freed if these functions returned an error. |
| |
| While at it, replace a 'ERR_PTR(-ENOMEM)' by a more generic |
| 'ERR_PTR(error)' as in the future zcomp_strm_{multi,siggle}_create() |
| could return other error codes. Function documentation updated |
| accordingly. |
| |
| Fixes: beca3ec71fe5 ("zram: add multi stream functionality") |
| Signed-off-by: Luis Henriques <luis.henriques@canonical.com> |
| Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> |
| Acked-by: Minchan Kim <minchan@kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/block/zram/zcomp.c | 12 +++++++----- |
| 1 file changed, 7 insertions(+), 5 deletions(-) |
| |
| --- a/drivers/block/zram/zcomp.c |
| +++ b/drivers/block/zram/zcomp.c |
| @@ -330,12 +330,14 @@ void zcomp_destroy(struct zcomp *comp) |
| * allocate new zcomp and initialize it. return compressing |
| * backend pointer or ERR_PTR if things went bad. ERR_PTR(-EINVAL) |
| * if requested algorithm is not supported, ERR_PTR(-ENOMEM) in |
| - * case of allocation error. |
| + * case of allocation error, or any other error potentially |
| + * returned by functions zcomp_strm_{multi,single}_create. |
| */ |
| struct zcomp *zcomp_create(const char *compress, int max_strm) |
| { |
| struct zcomp *comp; |
| struct zcomp_backend *backend; |
| + int error; |
| |
| backend = find_backend(compress); |
| if (!backend) |
| @@ -347,12 +349,12 @@ struct zcomp *zcomp_create(const char *c |
| |
| comp->backend = backend; |
| if (max_strm > 1) |
| - zcomp_strm_multi_create(comp, max_strm); |
| + error = zcomp_strm_multi_create(comp, max_strm); |
| else |
| - zcomp_strm_single_create(comp); |
| - if (!comp->stream) { |
| + error = zcomp_strm_single_create(comp); |
| + if (error) { |
| kfree(comp); |
| - return ERR_PTR(-ENOMEM); |
| + return ERR_PTR(error); |
| } |
| return comp; |
| } |