* [PATCH 4.19 1/1] ida: Fix crash in ida_free when the bitmap is empty
2024-08-30 8:29 [PATCH 4.19 0/1] Fix CVE-2023-6915 hsimeliere.opensource
@ 2024-08-30 8:29 ` hsimeliere.opensource
2024-08-30 13:05 ` Greg KH
0 siblings, 1 reply; 3+ messages in thread
From: hsimeliere.opensource @ 2024-08-30 8:29 UTC (permalink / raw)
To: stable
Cc: Matthew Wilcox (Oracle), Zhenghan Wang, Linus Torvalds,
Hugo SIMELIERE
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;
--
2.43.0
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