From 473e90b2e8356f084dcf9c815a5170d4d4925897 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Fri, 19 May 2017 11:39:13 +0200 Subject: [PATCH] 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 Signed-off-by: Elena Reshetova Signed-off-by: Borislav Petkov Reviewed-by: Hans Liljestrand Reviewed-by: David Windsor Cc: Tony Luck Cc: Yazen Ghannam Cc: linux-edac Link: http://lkml.kernel.org/r/1492695536-5947-1-git-send-email-elena.reshetova@intel.com Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/amd_nb.h | 3 ++- arch/x86/kernel/cpu/mcheck/mce_amd.c | 6 +++--- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h index 00c88a01301d..da181ad1d5f8 100644 --- a/arch/x86/include/asm/amd_nb.h +++ b/arch/x86/include/asm/amd_nb.h @@ -3,6 +3,7 @@ #include #include +#include struct amd_nb_bus_dev_range { u8 bus; @@ -55,7 +56,7 @@ struct threshold_bank { struct threshold_block *blocks; /* initialized to the number of CPUs on the node sharing this bank */ - atomic_t cpus; + refcount_t cpus; }; struct amd_northbridge { diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c index 6e4a047e4b68..41439ab41102 100644 --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c @@ -1202,7 +1202,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank) goto out; per_cpu(threshold_banks, cpu)[bank] = b; - atomic_inc(&b->cpus); + refcount_inc(&b->cpus); err = __threshold_add_blocks(b); @@ -1225,7 +1225,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank) per_cpu(threshold_banks, cpu)[bank] = b; if (is_shared_bank(bank)) { - atomic_set(&b->cpus, 1); + refcount_set(&b->cpus, 1); /* nb is already initialized, see above */ if (nb) { @@ -1289,7 +1289,7 @@ static void threshold_remove_bank(unsigned int cpu, int bank) goto free_out; if (is_shared_bank(bank)) { - if (!atomic_dec_and_test(&b->cpus)) { + if (!refcount_dec_and_test(&b->cpus)) { __threshold_remove_blocks(b); per_cpu(threshold_banks, cpu)[bank] = NULL; return; -- 2.39.5