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tools/testing/selftests/sysctl/sysctl.sh: add proc_do_large_bitmap() test case

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The kernel has only two users of proc_do_large_bitmap(), the kernel CPU
watchdog, and the ip_local_reserved_ports.  Refer to watchdog_cpumask
and ip_local_reserved_ports in Documentation for further details on
these.  When you input a large buffer into these, when it is larger than
PAGE_SIZE- 1, the input data gets misparsed, and the user get
incorrectly informed that the desired input value was set.  This commit
implements a test which mimics and exploits that use case, it uses a
bitmap size, as in the watchdog case.  The bitmap is used to test the
bitmap proc handler, proc_do_large_bitmap().

The next commit fixes this issue.

[akpm@linux-foundation.org: move proc_do_large_bitmap() export to EOF]
[mcgrof@kernel.org: use new target description for backward compatibility]
[mcgrof@kernel.org: augment test number to 50, ran into issues with bash string comparisons when testing up to 50 cases.]
[mcgrof@kernel.org: introduce and use verify_diff_proc_file() to use diff]
[mcgrof@kernel.org: use mktemp for tmp file]
[mcgrof@kernel.org: merge shell test and C code]
[mcgrof@kernel.org: commit log love]
[mcgrof@kernel.org: export proc_do_large_bitmap() to allow for the test
[mcgrof@kernel.org: check for the return value when writing to the proc file]
Link: http://lkml.kernel.org/r/20190320222831.8243-6-mcgrof@kernel.org
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Eric Sandeen
2019-05-14 15:45:10 -07:00
committed by Linus Torvalds
parent a0edef7968
commit 2ea622b887
2 changed files with 97 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
lib/test_sysctl.c
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@@ -47,6 +47,9 @@ struct test_sysctl_data {
unsigned int uint_0001;
char string_0001[65];
#define SYSCTL_TEST_BITMAP_SIZE 65536
unsigned long *bitmap_0001;
};
static struct test_sysctl_data test_data = {
@@ -102,6 +105,13 @@ static struct ctl_table test_table[] = {
.mode = 0644,
.proc_handler = proc_dostring,
},
{
.procname = "bitmap_0001",
.data = &test_data.bitmap_0001,
.maxlen = SYSCTL_TEST_BITMAP_SIZE,
.mode = 0644,
.proc_handler = proc_do_large_bitmap,
},
{ }
};
@@ -129,15 +139,21 @@ static struct ctl_table_header *test_sysctl_header;
static int __init test_sysctl_init(void)
{
test_sysctl_header = register_sysctl_table(test_sysctl_root_table);
if (!test_sysctl_header)
test_data.bitmap_0001 = kzalloc(SYSCTL_TEST_BITMAP_SIZE/8, GFP_KERNEL);
if (!test_data.bitmap_0001)
return -ENOMEM;
test_sysctl_header = register_sysctl_table(test_sysctl_root_table);
if (!test_sysctl_header) {
kfree(test_data.bitmap_0001);
return -ENOMEM;
}
return 0;
}
late_initcall(test_sysctl_init);
static void __exit test_sysctl_exit(void)
{
kfree(test_data.bitmap_0001);
if (test_sysctl_header)
unregister_sysctl_table(test_sysctl_header);
}