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x86/mce: Convert threshold_bank.cpus from atomic_t to refcount_t
The refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Suggested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Reviewed-by: David Windsor <dwindsor@gmail.com> Cc: Tony Luck <tony.luck@intel.com> Cc: Yazen Ghannam <Yazen.Ghannam@amd.com> Cc: linux-edac <linux-edac@vger.kernel.org> Link: http://lkml.kernel.org/r/1492695536-5947-1-git-send-email-elena.reshetova@intel.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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2 changed files with 5 additions and 4 deletions
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@ -3,6 +3,7 @@
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#include <linux/ioport.h>
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#include <linux/pci.h>
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#include <linux/refcount.h>
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struct amd_nb_bus_dev_range {
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u8 bus;
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@ -55,7 +56,7 @@ struct threshold_bank {
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struct threshold_block *blocks;
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/* initialized to the number of CPUs on the node sharing this bank */
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atomic_t cpus;
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refcount_t cpus;
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};
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struct amd_northbridge {
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@ -1202,7 +1202,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank)
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goto out;
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per_cpu(threshold_banks, cpu)[bank] = b;
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atomic_inc(&b->cpus);
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refcount_inc(&b->cpus);
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err = __threshold_add_blocks(b);
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@ -1225,7 +1225,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank)
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per_cpu(threshold_banks, cpu)[bank] = b;
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if (is_shared_bank(bank)) {
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atomic_set(&b->cpus, 1);
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refcount_set(&b->cpus, 1);
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/* nb is already initialized, see above */
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if (nb) {
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@ -1289,7 +1289,7 @@ static void threshold_remove_bank(unsigned int cpu, int bank)
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goto free_out;
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if (is_shared_bank(bank)) {
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if (!atomic_dec_and_test(&b->cpus)) {
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if (!refcount_dec_and_test(&b->cpus)) {
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__threshold_remove_blocks(b);
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per_cpu(threshold_banks, cpu)[bank] = NULL;
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return;
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