Messages in this thread Patch in this message | | | Date | Tue, 15 Nov 2016 09:42:58 -0800 | From | tip-bot for Fenghua Yu <> | Subject | [tip:x86/cache] x86/intel_rdt: Protect info directory from removal |
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Commit-ID: f57b308728902d9ffade53466e9201e999a870e4 Gitweb: http://git.kernel.org/tip/f57b308728902d9ffade53466e9201e999a870e4 Author: Fenghua Yu <fenghua.yu@intel.com> AuthorDate: Fri, 11 Nov 2016 17:02:36 -0800 Committer: Thomas Gleixner <tglx@linutronix.de> CommitDate: Tue, 15 Nov 2016 18:35:49 +0100
x86/intel_rdt: Protect info directory from removal
The info directory and the per-resource subdirectories of the info directory have no reference to a struct rdtgroup in kn->priv. An attempt to remove one of those directories results in a NULL pointer dereference.
Protect the directories from removal and return -EPERM instead of -ENOENT.
[ tglx: Massaged changelog ]
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> Cc: "Ravi V Shankar" <ravi.v.shankar@intel.com> Cc: "Tony Luck" <tony.luck@intel.com> Cc: "Sai Prakhya" <sai.praneeth.prakhya@intel.com> Cc: "Vikas Shivappa" <vikas.shivappa@linux.intel.com> Cc: "Ingo Molnar" <mingo@elte.hu> Cc: "H. Peter Anvin" <h.peter.anvin@intel.com> Link: http://lkml.kernel.org/r/1478912558-55514-1-git-send-email-fenghua.yu@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
--- arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index 4795880..cff286e 100644 --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -644,16 +644,29 @@ static int parse_rdtgroupfs_options(char *data) */ static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn) { - if (kernfs_type(kn) == KERNFS_DIR) - return kn->priv; - else + if (kernfs_type(kn) == KERNFS_DIR) { + /* + * All the resource directories use "kn->priv" + * to point to the "struct rdtgroup" for the + * resource. "info" and its subdirectories don't + * have rdtgroup structures, so return NULL here. + */ + if (kn == kn_info || kn->parent == kn_info) + return NULL; + else + return kn->priv; + } else { return kn->parent->priv; + } } struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn) { struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn); + if (!rdtgrp) + return NULL; + atomic_inc(&rdtgrp->waitcount); kernfs_break_active_protection(kn); @@ -670,6 +683,9 @@ void rdtgroup_kn_unlock(struct kernfs_node *kn) { struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn); + if (!rdtgrp) + return; + mutex_unlock(&rdtgroup_mutex); if (atomic_dec_and_test(&rdtgrp->waitcount) && @@ -918,7 +934,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn) rdtgrp = rdtgroup_kn_lock_live(kn); if (!rdtgrp) { rdtgroup_kn_unlock(kn); - return -ENOENT; + return -EPERM; } /* Give any tasks back to the default group */
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