From: "Matthew Wilcox (Oracle)" willy@infradead.org

commit af73483f4e8b6f5c68c9aa63257bdd929a9c194a upstream.

The IDA usually detects double-frees, but that detection failed to consider the case when there are no nearby IDs allocated and so we have a NULL bitmap rather than simply having a clear bit. Add some tests to the test-suite to be sure we don't inadvertently reintroduce this problem. Unfortunately they're quite noisy so include a message to disregard the warnings.

Reported-by: Zhenghan Wang wzhmmmmm@gmail.com Signed-off-by: Matthew Wilcox (Oracle) willy@infradead.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Hugo SIMELIERE hsimeliere.opensource@witekio.com --- lib/idr.c | 2 +- lib/test_ida.c | 40 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/lib/idr.c b/lib/idr.c index 432a985bf772..3e4035fa89dd 100644 --- a/lib/idr.c +++ b/lib/idr.c @@ -471,7 +471,7 @@ static void ida_remove(struct ida *ida, int id) } else { btmp = bitmap->bitmap; } - if (!test_bit(offset, btmp)) + if (!bitmap || !test_bit(offset, btmp)) goto err;

__clear_bit(offset, btmp); diff --git a/lib/test_ida.c b/lib/test_ida.c index b06880625961..55105baa19da 100644 --- a/lib/test_ida.c +++ b/lib/test_ida.c @@ -150,6 +150,45 @@ static void ida_check_conv(struct ida *ida) IDA_BUG_ON(ida, !ida_is_empty(ida)); }

+/* + * Check various situations where we attempt to free an ID we don't own. + */ +static void ida_check_bad_free(struct ida *ida) +{ + unsigned long i; + + printk("vvv Ignore "not allocated" warnings\n"); + /* IDA is empty; all of these will fail */ + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a single value entry */ + IDA_BUG_ON(ida, ida_alloc_min(ida, 3, GFP_KERNEL) != 3); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a single bitmap */ + IDA_BUG_ON(ida, ida_alloc_min(ida, 1023, GFP_KERNEL) != 1023); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + + /* IDA contains a tree */ + IDA_BUG_ON(ida, ida_alloc_min(ida, (1 << 20) - 1, GFP_KERNEL) != (1 << 20) - 1); + ida_free(ida, 0); + for (i = 0; i < 31; i++) + ida_free(ida, 1 << i); + printk("^^^ "not allocated" warnings over\n"); + + ida_free(ida, 3); + ida_free(ida, 1023); + ida_free(ida, (1 << 20) - 1); + + IDA_BUG_ON(ida, !ida_is_empty(ida)); +} + static DEFINE_IDA(ida);

static int ida_checks(void) @@ -162,6 +201,7 @@ static int ida_checks(void) ida_check_leaf(&ida, 1024 * 64); ida_check_max(&ida); ida_check_conv(&ida); + ida_check_bad_free(&ida);

printk("IDA: %u of %u tests passed\n", tests_passed, tests_run); return (tests_run != tests_passed) ? 0 : -EINVAL;