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tools/mm: fix slabinfo crash when MAX_SLABS is exceeded

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The number of slabs can easily exceed the hard coded MAX_SLABS in the
slabinfo tool, causing it to overwrite memory and crash.

Increase the value of MAX_SLABS, and check if that has been exceeded for
each new slab, instead of at the end when it's already too late.  Also
move the check for MAX_ALIASES into the loop body.

Link: https://lkml.kernel.org/r/20241031105534.565533-1-marc.c.dionne@gmail.com
Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Marc Dionne 2024-10-31 07:55:34 -03:00 • committed by Andrew Morton
parent 431e106019
commit e3d37a6f62
1 changed files with 5 additions and 5 deletions
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10
tools/mm/slabinfo.c
View file

@ -21,7 +21,7 @@
#include <regex.h> #include <regex.h>
#include <errno.h> #include <errno.h>
#define MAX_SLABS 500 #define MAX_SLABS 2000
#define MAX_ALIASES 500 #define MAX_ALIASES 500
#define MAX_NODES 1024 #define MAX_NODES 1024
@ -1228,6 +1228,8 @@ static void read_slab_dir(void)
continue; continue;
switch (de->d_type) { switch (de->d_type) {
case DT_LNK: case DT_LNK:
if (alias - aliasinfo == MAX_ALIASES)
fatal("Too many aliases\n");
alias->name = strdup(de->d_name); alias->name = strdup(de->d_name);
count = readlink(de->d_name, buffer, sizeof(buffer)-1); count = readlink(de->d_name, buffer, sizeof(buffer)-1);
@ -1242,6 +1244,8 @@ static void read_slab_dir(void)
alias++; alias++;
break; break;
case DT_DIR: case DT_DIR:
if (slab - slabinfo == MAX_SLABS)
fatal("Too many slabs\n");
if (chdir(de->d_name)) if (chdir(de->d_name))
fatal("Unable to access slab %s\n", slab->name); fatal("Unable to access slab %s\n", slab->name);
slab->name = strdup(de->d_name); slab->name = strdup(de->d_name);
@ -1312,10 +1316,6 @@ static void read_slab_dir(void)
slabs = slab - slabinfo; slabs = slab - slabinfo;
actual_slabs = slabs; actual_slabs = slabs;
aliases = alias - aliasinfo; aliases = alias - aliasinfo;
if (slabs > MAX_SLABS)
fatal("Too many slabs\n");
if (aliases > MAX_ALIASES)
fatal("Too many aliases\n");
} }
static void output_slabs(void) static void output_slabs(void)