2021-06-10 16:47:29

by Colin King

Subject: [PATCH][next] cifsd: fix kfree of uninitialized pointer oid

From: Colin Ian King <[email protected]>

Currently function ksmbd_neg_token_init_mech_type can kfree an
uninitialized pointer oid when the call to asn1_oid_decode fails
when vlen is out of range. All the other failure cases in
function asn1_oid_decode set *oid to NULL on an error, so fix the
issue by ensuring the vlen out of range error also nullifies the
pointer.

Fixes: 8bae4419ce63 ("cifsd: add goto fail in neg_token_init_mech_type()")
Addresses-Coverity: ("Uninitialized pointer read")
Signed-off-by: Colin Ian King <[email protected]>
---
fs/cifsd/asn1.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/cifsd/asn1.c b/fs/cifsd/asn1.c
index 2c63a3e5618b..b014f4638610 100644
--- a/fs/cifsd/asn1.c
+++ b/fs/cifsd/asn1.c
@@ -66,7 +66,7 @@ static bool asn1_oid_decode(const unsigned char *value, size_t vlen,

vlen += 1;
if (vlen < 2 || vlen > UINT_MAX / sizeof(unsigned long))
- return false;
+ goto fail_nullify;

*oid = kmalloc(vlen * sizeof(unsigned long), GFP_KERNEL);
if (!*oid)
@@ -102,6 +102,7 @@ static bool asn1_oid_decode(const unsigned char *value, size_t vlen,

fail:
kfree(*oid);
+fail_nullify:
*oid = NULL;
return false;
}
--
2.31.1

2021-06-11 00:42:03

by Namjae Jeon

Subject: RE: [PATCH][next] cifsd: fix kfree of uninitialized pointer oid

> From: Colin Ian King <[email protected]>
>
> Currently function ksmbd_neg_token_init_mech_type can kfree an uninitialized pointer oid when the call
> to asn1_oid_decode fails when vlen is out of range. All the other failure cases in function
> asn1_oid_decode set *oid to NULL on an error, so fix the issue by ensuring the vlen out of range error
> also nullifies the pointer.
>
> Fixes: 8bae4419ce63 ("cifsd: add goto fail in neg_token_init_mech_type()")
> Addresses-Coverity: ("Uninitialized pointer read")
> Signed-off-by: Colin Ian King <[email protected]>
I will apply, Thanks for your patch!