diff options
| author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2023-10-09 08:31:52 -0700 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2023-10-12 09:15:15 +0200 |
| commit | e2bca4870fdaf855651ee80b083d892599c5d982 (patch) | |
| tree | e7b39472334d3b0ec8b61e3f5b61846a36ce2c9e | |
| parent | 71c299c711d1f44f0bf04f1fea66baad565240f1 (diff) | |
af_packet: Fix fortified memcpy() without flex array.
Sergei Trofimovich reported a regression [0] caused by commit a0ade8404c3b
("af_packet: Fix warning of fortified memcpy() in packet_getname().").
It introduced a flex array sll_addr_flex in struct sockaddr_ll as a
union-ed member with sll_addr to work around the fortified memcpy() check.
However, a userspace program uses a struct that has struct sockaddr_ll in
the middle, where a flex array is illegal to exist.
include/linux/if_packet.h:24:17: error: flexible array member 'sockaddr_ll::<unnamed union>::<unnamed struct>::sll_addr_flex' not at end of 'struct packet_info_t'
24 | __DECLARE_FLEX_ARRAY(unsigned char, sll_addr_flex);
| ^~~~~~~~~~~~~~~~~~~~
To fix the regression, let's go back to the first attempt [1] telling
memcpy() the actual size of the array.
Reported-by: Sergei Trofimovich <slyich@gmail.com>
Closes: https://github.com/NixOS/nixpkgs/pull/252587#issuecomment-1741733002 [0]
Link: https://lore.kernel.org/netdev/20230720004410.87588-3-kuniyu@amazon.com/ [1]
Fixes: a0ade8404c3b ("af_packet: Fix warning of fortified memcpy() in packet_getname().")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20231009153151.75688-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
| -rw-r--r-- | include/uapi/linux/if_packet.h | 6 | ||||
| -rw-r--r-- | net/packet/af_packet.c | 7 |
2 files changed, 7 insertions, 6 deletions
diff --git a/include/uapi/linux/if_packet.h b/include/uapi/linux/if_packet.h index 4d0ad22f83b5..9efc42382fdb 100644 --- a/include/uapi/linux/if_packet.h +++ b/include/uapi/linux/if_packet.h @@ -18,11 +18,7 @@ struct sockaddr_ll { unsigned short sll_hatype; unsigned char sll_pkttype; unsigned char sll_halen; - union { - unsigned char sll_addr[8]; - /* Actual length is in sll_halen. */ - __DECLARE_FLEX_ARRAY(unsigned char, sll_addr_flex); - }; + unsigned char sll_addr[8]; }; /* Packet types */ diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 8f97648d652f..a84e00b5904b 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3607,7 +3607,12 @@ static int packet_getname(struct socket *sock, struct sockaddr *uaddr, if (dev) { sll->sll_hatype = dev->type; sll->sll_halen = dev->addr_len; - memcpy(sll->sll_addr_flex, dev->dev_addr, dev->addr_len); + + /* Let __fortify_memcpy_chk() know the actual buffer size. */ + memcpy(((struct sockaddr_storage *)sll)->__data + + offsetof(struct sockaddr_ll, sll_addr) - + offsetofend(struct sockaddr_ll, sll_family), + dev->dev_addr, dev->addr_len); } else { sll->sll_hatype = 0; /* Bad: we have no ARPHRD_UNSPEC */ sll->sll_halen = 0; |