Commit 9cf11ce0 authored by Mikulas Patocka's avatar Mikulas Patocka Committed by Mike Snitzer
Browse files

dm stats: limit the number of entries 



The kvmalloc function fails with a warning if the size is larger than
INT_MAX. Linus said that there should be limits that prevent this warning
from being hit. This commit adds the limits to the dm-stats subsystem
in DM core.

Signed-off-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Signed-off-by: default avatarMike Snitzer <snitzer@kernel.org>
parent bd504bcf

drivers/md/dm-stats.c

+9 −0
Original line number Diff line number Diff line
@@ -66,6 +66,9 @@ struct dm_stats_last_position { 
	unsigned int last_rw;

};



#define DM_STAT_MAX_ENTRIES		8388608

#define DM_STAT_MAX_HISTOGRAM_ENTRIES	134217728



/*

 * A typo on the command line could possibly make the kernel run out of memory

 * and crash. To prevent the crash we account all used memory. We fail if we
@@ -285,6 +288,9 @@ static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end, 
	if (n_entries != (size_t)n_entries || !(size_t)(n_entries + 1))

		return -EOVERFLOW;



	if (n_entries > DM_STAT_MAX_ENTRIES)

		return -EOVERFLOW;



	shared_alloc_size = struct_size(s, stat_shared, n_entries);

	if ((shared_alloc_size - sizeof(struct dm_stat)) / sizeof(struct dm_stat_shared) != n_entries)

		return -EOVERFLOW;
@@ -297,6 +303,9 @@ static int dm_stats_create(struct dm_stats *stats, sector_t start, sector_t end, 
	if (histogram_alloc_size / (n_histogram_entries + 1) != (size_t)n_entries * sizeof(unsigned long long))

		return -EOVERFLOW;



	if ((n_histogram_entries + 1) * (size_t)n_entries > DM_STAT_MAX_HISTOGRAM_ENTRIES)

		return -EOVERFLOW;



	if (!check_shared_memory(shared_alloc_size + histogram_alloc_size +

				 num_possible_cpus() * (percpu_alloc_size + histogram_alloc_size)))

		return -ENOMEM;