* [PATCH][next] pstore/zone: fix dereference of pointer before it has been null checked
@ 2020-05-12 17:19 Colin King
2020-05-12 18:59 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Colin King @ 2020-05-12 17:19 UTC (permalink / raw)
To: Kees Cook, Anton Vorontsov, Colin Cross, Tony Luck, WeiXiong Liao
Cc: kernel-janitors, linux-kernel
From: Colin Ian King <colin.king@canonical.com>
Currently the assignment of cnt dereferences pointer 'record' before
the pointer has been null checked. Fix this by only making this
dereference after it has been null checked close to the point cnt
is to be used.
Addresses-Coverity: ("Dereference before null check")
Fixes: 637ce64e7f57 ("pstore/zone,blk: Add support for pmsg frontend")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
fs/pstore/zone.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c
index c5bf3b9f644f..3cf7d6762c76 100644
--- a/fs/pstore/zone.c
+++ b/fs/pstore/zone.c
@@ -825,7 +825,7 @@ static int notrace psz_record_write(struct pstore_zone *zone,
struct pstore_record *record)
{
size_t start, rem;
- int cnt = record->size;
+ int cnt;
bool is_full_data = false;
char *buf = record->buf;
@@ -835,6 +835,7 @@ static int notrace psz_record_write(struct pstore_zone *zone,
if (atomic_read(&zone->buffer->datalen) >= zone->buffer_size)
is_full_data = true;
+ cnt = record->size;
if (unlikely(cnt > zone->buffer_size)) {
buf += cnt - zone->buffer_size;
cnt = zone->buffer_size;
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH][next] pstore/zone: fix dereference of pointer before it has been null checked
2020-05-12 17:19 [PATCH][next] pstore/zone: fix dereference of pointer before it has been null checked Colin King
@ 2020-05-12 18:59 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2020-05-12 18:59 UTC (permalink / raw)
To: Colin King
Cc: Anton Vorontsov, Colin Cross, Tony Luck, WeiXiong Liao,
kernel-janitors, linux-kernel
On Tue, May 12, 2020 at 06:19:32PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Currently the assignment of cnt dereferences pointer 'record' before
> the pointer has been null checked. Fix this by only making this
> dereference after it has been null checked close to the point cnt
> is to be used.
>
> Addresses-Coverity: ("Dereference before null check")
> Fixes: 637ce64e7f57 ("pstore/zone,blk: Add support for pmsg frontend")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> fs/pstore/zone.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c
> index c5bf3b9f644f..3cf7d6762c76 100644
> --- a/fs/pstore/zone.c
> +++ b/fs/pstore/zone.c
> @@ -825,7 +825,7 @@ static int notrace psz_record_write(struct pstore_zone *zone,
> struct pstore_record *record)
> {
> size_t start, rem;
> - int cnt = record->size;
> + int cnt;
> bool is_full_data = false;
> char *buf = record->buf;
Also here. I'll fix both. Thanks!
-Kees
>
> @@ -835,6 +835,7 @@ static int notrace psz_record_write(struct pstore_zone *zone,
> if (atomic_read(&zone->buffer->datalen) >= zone->buffer_size)
> is_full_data = true;
>
> + cnt = record->size;
> if (unlikely(cnt > zone->buffer_size)) {
> buf += cnt - zone->buffer_size;
> cnt = zone->buffer_size;
> --
> 2.25.1
>
--
Kees Cook
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