Messages in this thread | | | Date | Fri, 28 Jan 2022 22:34:27 +0800 | Subject | Re: [PATCH] bcache: Fix a NULL or wild pointer dereference in btree_gc_rewrite_node() | From | Coly Li <> |
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On 1/28/22 6:17 PM, Greg KH wrote: > On Tue, Jan 25, 2022 at 12:47:01AM +0800, Zhou Qingyang wrote: >> In btree_gc_rewrite_node(), btree_node_alloc_replacement() is assigned to >> n and return error code or NULL on failure. n is passed to >> bch_btree_node_write_sync() and there is a dereference of it in >> bch_btree_node_write_sync() without checks, which may lead to wild >> pointer dereference or NULL pointer dereference depending on n. >> >> Fix this bug by adding IS_ERR_OR_NULL check of n. >> >> This bug was found by a static analyzer. >> >> Builds with 'make allyesconfig' show no new warnings, >> and our static analyzer no longer warns about this code. >> >> Fixes: ("bcache: Rework btree cache reserve handling") >> Signed-off-by: Zhou Qingyang <zhou1615@umn.edu> >> --- >> The analysis employs differential checking to identify inconsistent >> security operations (e.g., checks or kfrees) between two code paths >> and confirms that the inconsistent operations are not recovered in the >> current function or the callers, so they constitute bugs. >> >> Note that, as a bug found by static analysis, it can be a false >> positive or hard to trigger. Multiple researchers have cross-reviewed >> the bug. >> >> drivers/md/bcache/btree.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c >> index 88c573eeb598..06d42292e86c 100644 >> --- a/drivers/md/bcache/btree.c >> +++ b/drivers/md/bcache/btree.c >> @@ -1504,6 +1504,8 @@ static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op, >> return 0; >> >> n = btree_node_alloc_replacement(replace, NULL); >> + if (IS_ERR_OR_NULL(n)) >> + return 0; >> >> /* recheck reserve after allocating replacement node */ >> if (btree_check_reserve(b, NULL)) { >> -- >> 2.25.1 >> > As stated before, umn.edu is still not allowed to contribute to the > Linux kernel. Please work with your administration to resolve this > issue. >
Copied. Thanks for the reminding.
Coly Li
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