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dm stats: limit the number of entries

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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: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
This commit is contained in:
Mikulas Patocka 2024-01-09 15:59:15 +01:00 committed by Mike Snitzer
parent bd504bcfec
commit 9cf11ce06e
1 changed files with 9 additions and 0 deletions
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9
drivers/md/dm-stats.c
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@ -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;