Commit d7f06bdd authored by Phil Auld's avatar Phil Auld Committed by Greg Kroah-Hartman
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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: 7ee951ac ("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: default avatarfeng xiangjun <fengxj325@gmail.com>
Signed-off-by: default avatarPhil Auld <pauld@redhat.com>
Signed-off-by: default avatarYury Norov <yury.norov@gmail.com>
Link: https://lore.kernel.org/r/20220906203542.1796629-1-pauld@redhat.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d8ab4685

include/linux/cpumask.h

+3 −2
Original line number Diff line number Diff line
@@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask, 
 * cover a worst-case of every other cpu being on one of two nodes for a

 * very large NR_CPUS.

 *

 *  Use PAGE_SIZE as a minimum for smaller configurations.

 *  Use PAGE_SIZE as a minimum for smaller configurations while avoiding

 *  unsigned comparison to -1.

 */

#define CPUMAP_FILE_MAX_BYTES  ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \

#define CPUMAP_FILE_MAX_BYTES  (((NR_CPUS * 9)/32 > PAGE_SIZE) \

					? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE)

#define CPULIST_FILE_MAX_BYTES  (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE)