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drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES
As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3. This leads to very large file sizes: topology$ ls -l total 0 -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list Adjust the inequality to catch the case when NR_CPUS is configured to a small value. Fixes: 7ee951a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist") Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "Rafael J. Wysocki" <rafael@kernel.org> Cc: Yury Norov <yury.norov@gmail.com> Cc: stable@vger.kernel.org Cc: feng xiangjun <fengxj325@gmail.com> Reported-by: feng xiangjun <fengxj325@gmail.com> Signed-off-by: Phil Auld <pauld@redhat.com> Signed-off-by: Yury Norov <yury.norov@gmail.com> Link: https://lore.kernel.org/r/20220906203542.1796629-1-pauld@redhat.com Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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include/linux/cpumask.h

Lines changed: 3 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask,
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* cover a worst-case of every other cpu being on one of two nodes for a
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* very large NR_CPUS.
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*
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* Use PAGE_SIZE as a minimum for smaller configurations.
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* Use PAGE_SIZE as a minimum for smaller configurations while avoiding
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* unsigned comparison to -1.
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*/
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#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \
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#define CPUMAP_FILE_MAX_BYTES (((NR_CPUS * 9)/32 > PAGE_SIZE) \
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? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)
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#define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE)
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