From: Waiman Long <longman@redhat.com> To: Andrew Morton <akpm@linux-foundation.org>, David Howells <dhowells@redhat.com> Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>, James Morris <jmorris@namei.org>, "Serge E. Hallyn" <serge@hallyn.com>, linux-mm@kvack.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@linux-foundation.org>, Joe Perches <joe@perches.com>, Matthew Wilcox <willy@infradead.org>, David Rientjes <rientjes@google.com> Subject: Re: [PATCH v3] mm: Add kvfree_sensitive() for freeing sensitive data objects Date: Wed, 06 May 2020 01:29:58 +0000 [thread overview] Message-ID: <3be0ef1d-fe7f-6b02-d9c0-c6b750fd94f3@redhat.com> (raw) In-Reply-To: <20200505133521.eb8901d0b92e09452191ab49@linux-foundation.org> On 5/5/20 4:35 PM, Andrew Morton wrote: > On Tue, 07 Apr 2020 21:21:57 +0100 David Howells <dhowells@redhat.com> wrote: > >> David Howells <dhowells@redhat.com> wrote: >> >>>> if (unlikely(key_data)) >>>> - __kvzfree(key_data, key_data_len); >>>> + kvfree_sensitive(key_data, key_data_len); >>> I think the if-statement is redundant. >> Ah - I see that you explicitly wanted to keep it. > Why's that? There is a comment above it: /* * The key may change (unlikely) in between 2 consecutive * __keyctl_read_key() calls. In this case, we reallocate * a larger buffer and redo the key read when * key_data_len < ret <= buflen. */ if (ret > key_data_len) { if (unlikely(key_data)) __kvzfree(key_data, key_data_len); key_data will be defined only if the unlikely case that the key increase in length between the 2 consecutive __keyctl_read_key() call and we have to enlarge the buffer and read the key again. I want to keep the unlikely() macro to emphasize the fact that this condition should not happen. >> There's a good chance it'll get janitored at some point. > Indeed. Perhaps add a few little comments to explain the reasoning and > to keep the janitorial fingers away? > I can reword the comment to make it more explicit and send a v4 if you think the current comment is not clear enough. Cheers, Longman
WARNING: multiple messages have this Message-ID (diff)
From: Waiman Long <longman@redhat.com> To: Andrew Morton <akpm@linux-foundation.org>, David Howells <dhowells@redhat.com> Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>, James Morris <jmorris@namei.org>, "Serge E. Hallyn" <serge@hallyn.com>, linux-mm@kvack.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@linux-foundation.org>, Joe Perches <joe@perches.com>, Matthew Wilcox <willy@infradead.org>, David Rientjes <rientjes@google.com> Subject: Re: [PATCH v3] mm: Add kvfree_sensitive() for freeing sensitive data objects Date: Tue, 5 May 2020 21:29:58 -0400 [thread overview] Message-ID: <3be0ef1d-fe7f-6b02-d9c0-c6b750fd94f3@redhat.com> (raw) In-Reply-To: <20200505133521.eb8901d0b92e09452191ab49@linux-foundation.org> On 5/5/20 4:35 PM, Andrew Morton wrote: > On Tue, 07 Apr 2020 21:21:57 +0100 David Howells <dhowells@redhat.com> wrote: > >> David Howells <dhowells@redhat.com> wrote: >> >>>> if (unlikely(key_data)) >>>> - __kvzfree(key_data, key_data_len); >>>> + kvfree_sensitive(key_data, key_data_len); >>> I think the if-statement is redundant. >> Ah - I see that you explicitly wanted to keep it. > Why's that? There is a comment above it: /* * The key may change (unlikely) in between 2 consecutive * __keyctl_read_key() calls. In this case, we reallocate * a larger buffer and redo the key read when * key_data_len < ret <= buflen. */ if (ret > key_data_len) { if (unlikely(key_data)) __kvzfree(key_data, key_data_len); key_data will be defined only if the unlikely case that the key increase in length between the 2 consecutive __keyctl_read_key() call and we have to enlarge the buffer and read the key again. I want to keep the unlikely() macro to emphasize the fact that this condition should not happen. >> There's a good chance it'll get janitored at some point. > Indeed. Perhaps add a few little comments to explain the reasoning and > to keep the janitorial fingers away? > I can reword the comment to make it more explicit and send a v4 if you think the current comment is not clear enough. Cheers, Longman
next prev parent reply other threads:[~2020-05-06 1:29 UTC|newest] Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-04-07 20:03 [PATCH v3] mm: Add kvfree_sensitive() for freeing sensitive data objects Waiman Long 2020-04-07 20:03 ` Waiman Long 2020-04-07 20:09 ` Linus Torvalds 2020-04-07 20:09 ` Linus Torvalds 2020-04-07 20:09 ` Linus Torvalds 2020-04-07 20:19 ` David Howells 2020-04-07 20:19 ` David Howells 2020-04-07 20:24 ` Waiman Long 2020-04-07 20:24 ` Waiman Long 2020-04-07 20:21 ` David Howells 2020-04-07 20:21 ` David Howells 2020-04-07 20:21 ` David Howells 2020-05-05 20:35 ` Andrew Morton 2020-05-05 20:35 ` Andrew Morton 2020-05-06 1:29 ` Waiman Long [this message] 2020-05-06 1:29 ` Waiman Long 2020-04-07 20:31 ` Joe Perches 2020-04-07 20:31 ` Joe Perches 2020-04-07 20:31 ` Joe Perches 2020-04-07 20:45 ` Waiman Long 2020-04-07 20:45 ` Waiman Long 2020-04-07 21:01 ` Linus Torvalds 2020-04-07 21:01 ` Linus Torvalds 2020-04-07 21:01 ` Linus Torvalds 2020-04-07 21:24 ` Uladzislau Rezki 2020-04-07 21:24 ` Uladzislau Rezki 2020-04-07 21:30 ` Linus Torvalds 2020-04-07 21:30 ` Linus Torvalds 2020-04-07 21:30 ` Linus Torvalds 2020-04-07 22:12 ` Matthew Wilcox 2020-04-07 22:12 ` Matthew Wilcox 2020-04-08 0:35 ` Joe Perches 2020-04-08 0:35 ` Joe Perches 2020-04-08 0:35 ` Joe Perches 2020-04-08 13:38 ` Jarkko Sakkinen 2020-04-08 13:38 ` Jarkko Sakkinen 2020-05-01 23:22 ` Eric Biggers 2020-05-01 23:22 ` Eric Biggers 2020-05-04 2:57 ` Waiman Long 2020-05-04 2:57 ` Waiman Long 2020-05-14 11:00 ` Balbir Singh 2020-05-14 11:00 ` Balbir Singh 2020-05-14 12:00 ` Matthew Wilcox 2020-05-14 12:00 ` Matthew Wilcox 2020-05-14 12:08 ` Joe Perches 2020-05-14 12:08 ` Joe Perches 2020-05-14 12:08 ` Joe Perches 2020-05-17 0:27 ` Balbir Singh 2020-05-17 0:27 ` Balbir Singh 2020-05-17 0:44 ` Matthew Wilcox 2020-05-17 0:44 ` Matthew Wilcox 2020-05-18 2:39 ` Waiman Long 2020-05-18 2:39 ` Waiman Long
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