[PATCH 5.4 032/408] net: Properly typecast int values to set sk_max_pacing_rate

Greg Kroah-Hartman
2020-10-27T14:30:42Z

From: Ke Li <keli@akamai.com>

[ Upstream commit 700465fd338fe5df08a1b2e27fa16981f562547f ]

In setsockopt(SO_MAX_PACING_RATE) on 64bit systems, sk_max_pacing_rate,
after extended from 'u32' to 'unsigned long', takes unintentionally
hiked value whenever assigned from an 'int' value with MSB=1, due to
binary sign extension in promoting s32 to u64, e.g. 0x80000000 becomes
0xFFFFFFFF80000000.

Thus inflated sk_max_pacing_rate causes subsequent getsockopt to return
~0U unexpectedly. It may also result in increased pacing rate.

Fix by explicitly casting the 'int' value to 'unsigned int' before
assigning it to sk_max_pacing_rate, for zero extension to happen.

Fixes: 76a9ebe811fb ("net: extend sk_pacing_rate to unsigned long")
Signed-off-by: Ji Li <jli@akamai.com>
Signed-off-by: Ke Li <keli@akamai.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20201022064146.79873-1-keli@akamai.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/filter.c | 3 ++-
net/core/sock.c | 2 +-
2 files changed, 3 insertions(+), 2 deletions(-)

--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -4270,7 +4270,8 @@ BPF_CALL_5(bpf_setsockopt, struct bpf_so
cmpxchg(&sk->sk_pacing_status,
SK_PACING_NONE,
SK_PACING_NEEDED);
- sk->sk_max_pacing_rate = (val == ~0U) ? ~0UL : val;
+ sk->sk_max_pacing_rate = (val == ~0U) ?
+ ~0UL : (unsigned int)val;
sk->sk_pacing_rate = min(sk->sk_pacing_rate,
sk->sk_max_pacing_rate);
break;
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1106,7 +1106,7 @@ set_rcvbuf:

case SO_MAX_PACING_RATE:
{
- unsigned long ulval = (val == ~0U) ? ~0UL : val;
+ unsigned long ulval = (val == ~0U) ? ~0UL : (unsigned int)val;

if (sizeof(ulval) != sizeof(val) &&
optlen >= sizeof(ulval) &&