From: Michal Hocko <mhocko@kernel.org> To: "Gustavo A. R. Silva" <garsilva@embeddedor.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: add NULL check to avoid potential NULL pointer dereference Date: Wed, 31 May 2017 17:09:23 +0200 [thread overview] Message-ID: <20170531150922.GA28694@dhcp22.suse.cz> (raw) In-Reply-To: <20170530212436.GA6195@embeddedgus> On Tue 30-05-17 16:24:36, Gustavo A. R. Silva wrote: > NULL check at line 1226: if (!pgdat), implies that pointer pgdat > might be NULL. > Function rollback_node_hotadd() dereference this pointer. > Add NULL check to avoid a potential NULL pointer dereference. The changelog is quite cryptic to be honest. Well the code is as well but what do you say about the following replacement. " If a new pgdat has to be allocated in add_memory_resource and the initialization fails for some reason we have to rollback_node_hotadd. This, however, assumes that pgdat allocation itself is successful which cannot be assumed. Add a check for pgdat to cover that case and skip rollback_node_hotadd altogether because there is nothing to roll back. This has been pointed out by coverity. " > > Addresses-Coverity-ID: 1369133 > Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/memory_hotplug.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 599c675..ea3bc3e 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1273,7 +1273,7 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online) > > error: > /* rollback pgdat allocation and others */ > - if (new_pgdat) > + if (new_pgdat && pgdat) > rollback_node_hotadd(nid, pgdat); > memblock_remove(start, size); > > -- > 2.5.0 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> -- Michal Hocko SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: "Gustavo A. R. Silva" <garsilva@embeddedor.com> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: add NULL check to avoid potential NULL pointer dereference Date: Wed, 31 May 2017 17:09:23 +0200 [thread overview] Message-ID: <20170531150922.GA28694@dhcp22.suse.cz> (raw) In-Reply-To: <20170530212436.GA6195@embeddedgus> On Tue 30-05-17 16:24:36, Gustavo A. R. Silva wrote: > NULL check at line 1226: if (!pgdat), implies that pointer pgdat > might be NULL. > Function rollback_node_hotadd() dereference this pointer. > Add NULL check to avoid a potential NULL pointer dereference. The changelog is quite cryptic to be honest. Well the code is as well but what do you say about the following replacement. " If a new pgdat has to be allocated in add_memory_resource and the initialization fails for some reason we have to rollback_node_hotadd. This, however, assumes that pgdat allocation itself is successful which cannot be assumed. Add a check for pgdat to cover that case and skip rollback_node_hotadd altogether because there is nothing to roll back. This has been pointed out by coverity. " > > Addresses-Coverity-ID: 1369133 > Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com> Acked-by: Michal Hocko <mhocko@suse.com> > --- > mm/memory_hotplug.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 599c675..ea3bc3e 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1273,7 +1273,7 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online) > > error: > /* rollback pgdat allocation and others */ > - if (new_pgdat) > + if (new_pgdat && pgdat) > rollback_node_hotadd(nid, pgdat); > memblock_remove(start, size); > > -- > 2.5.0 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-05-31 15:09 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-05-30 21:24 [PATCH] mm: add NULL check to avoid potential NULL pointer dereference Gustavo A. R. Silva 2017-05-30 21:24 ` Gustavo A. R. Silva 2017-05-31 15:09 ` Michal Hocko [this message] 2017-05-31 15:09 ` Michal Hocko
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