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[PULL 02/11] Fix unsigned integer underflow in fd-trans.c
From: |
Laurent Vivier |
Subject: |
[PULL 02/11] Fix unsigned integer underflow in fd-trans.c |
Date: |
Tue, 22 Oct 2019 10:10:55 +0200 |
From: Shu-Chun Weng <address@hidden>
In any of these `*_for_each_*` functions, the last entry in the buffer (so the
"remaining length in the buffer" `len` is equal to the length of the
entry `nlmsg_len`/`nla_len`/etc) has size that is not a multiple of the
alignment, the aligned lengths `*_ALIGN(*_len)` will be greater than `len`.
Since `len` is unsigned (`size_t`), it underflows and the loop will read
pass the buffer.
This may manifest as random EINVAL or EOPNOTSUPP error on IO or network
system calls.
Signed-off-by: Shu-Chun Weng <address@hidden>
Reviewed-by: Laurent Vivier <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Laurent Vivier <address@hidden>
---
linux-user/fd-trans.c | 51 +++++++++++++++++++++++++++++++++----------
1 file changed, 40 insertions(+), 11 deletions(-)
diff --git a/linux-user/fd-trans.c b/linux-user/fd-trans.c
index 60077ce5319d..9b92386abf51 100644
--- a/linux-user/fd-trans.c
+++ b/linux-user/fd-trans.c
@@ -279,6 +279,7 @@ static abi_long host_to_target_for_each_nlmsg(struct
nlmsghdr *nlh,
(struct nlmsghdr *))
{
uint32_t nlmsg_len;
+ uint32_t aligned_nlmsg_len;
abi_long ret;
while (len > sizeof(struct nlmsghdr)) {
@@ -312,8 +313,13 @@ static abi_long host_to_target_for_each_nlmsg(struct
nlmsghdr *nlh,
break;
}
tswap_nlmsghdr(nlh);
- len -= NLMSG_ALIGN(nlmsg_len);
- nlh = (struct nlmsghdr *)(((char*)nlh) + NLMSG_ALIGN(nlmsg_len));
+
+ aligned_nlmsg_len = NLMSG_ALIGN(nlmsg_len);
+ if (aligned_nlmsg_len >= len) {
+ break;
+ }
+ len -= aligned_nlmsg_len;
+ nlh = (struct nlmsghdr *)(((char*)nlh) + aligned_nlmsg_len);
}
return 0;
}
@@ -323,6 +329,7 @@ static abi_long target_to_host_for_each_nlmsg(struct
nlmsghdr *nlh,
abi_long (*target_to_host_nlmsg)
(struct nlmsghdr *))
{
+ uint32_t aligned_nlmsg_len;
int ret;
while (len > sizeof(struct nlmsghdr)) {
@@ -349,8 +356,13 @@ static abi_long target_to_host_for_each_nlmsg(struct
nlmsghdr *nlh,
return ret;
}
}
- len -= NLMSG_ALIGN(nlh->nlmsg_len);
- nlh = (struct nlmsghdr *)(((char *)nlh) + NLMSG_ALIGN(nlh->nlmsg_len));
+
+ aligned_nlmsg_len = NLMSG_ALIGN(nlh->nlmsg_len);
+ if (aligned_nlmsg_len >= len) {
+ break;
+ }
+ len -= aligned_nlmsg_len;
+ nlh = (struct nlmsghdr *)(((char *)nlh) + aligned_nlmsg_len);
}
return 0;
}
@@ -363,6 +375,7 @@ static abi_long host_to_target_for_each_nlattr(struct
nlattr *nlattr,
void *context))
{
unsigned short nla_len;
+ unsigned short aligned_nla_len;
abi_long ret;
while (len > sizeof(struct nlattr)) {
@@ -377,8 +390,13 @@ static abi_long host_to_target_for_each_nlattr(struct
nlattr *nlattr,
if (ret < 0) {
return ret;
}
- len -= NLA_ALIGN(nla_len);
- nlattr = (struct nlattr *)(((char *)nlattr) + NLA_ALIGN(nla_len));
+
+ aligned_nla_len = NLA_ALIGN(nla_len);
+ if (aligned_nla_len >= len) {
+ break;
+ }
+ len -= aligned_nla_len;
+ nlattr = (struct nlattr *)(((char *)nlattr) + aligned_nla_len);
}
return 0;
}
@@ -389,6 +407,7 @@ static abi_long host_to_target_for_each_rtattr(struct
rtattr *rtattr,
(struct rtattr *))
{
unsigned short rta_len;
+ unsigned short aligned_rta_len;
abi_long ret;
while (len > sizeof(struct rtattr)) {
@@ -403,8 +422,13 @@ static abi_long host_to_target_for_each_rtattr(struct
rtattr *rtattr,
if (ret < 0) {
return ret;
}
- len -= RTA_ALIGN(rta_len);
- rtattr = (struct rtattr *)(((char *)rtattr) + RTA_ALIGN(rta_len));
+
+ aligned_rta_len = RTA_ALIGN(rta_len);
+ if (aligned_rta_len >= len) {
+ break;
+ }
+ len -= aligned_rta_len;
+ rtattr = (struct rtattr *)(((char *)rtattr) + aligned_rta_len);
}
return 0;
}
@@ -1058,6 +1082,7 @@ static abi_long target_to_host_for_each_rtattr(struct
rtattr *rtattr,
abi_long
(*target_to_host_rtattr)
(struct rtattr *))
{
+ unsigned short aligned_rta_len;
abi_long ret;
while (len >= sizeof(struct rtattr)) {
@@ -1071,9 +1096,13 @@ static abi_long target_to_host_for_each_rtattr(struct
rtattr *rtattr,
if (ret < 0) {
return ret;
}
- len -= RTA_ALIGN(rtattr->rta_len);
- rtattr = (struct rtattr *)(((char *)rtattr) +
- RTA_ALIGN(rtattr->rta_len));
+
+ aligned_rta_len = RTA_ALIGN(rtattr->rta_len);
+ if (aligned_rta_len >= len) {
+ break;
+ }
+ len -= aligned_rta_len;
+ rtattr = (struct rtattr *)(((char *)rtattr) + aligned_rta_len);
}
return 0;
}
--
2.21.0
- [PULL 00/11] Linux user for 4.2 patches, Laurent Vivier, 2019/10/22
- [PULL 04/11] linux-user/strace: Add print_timezone(), Laurent Vivier, 2019/10/22
- [PULL 10/11] linux-user/strace: Let print_sockaddr() have a 'last' argument, Laurent Vivier, 2019/10/22
- [PULL 06/11] linux-user/syscall: Introduce target_sockaddr_nl, Laurent Vivier, 2019/10/22
- [PULL 07/11] linux-user/strace: Dump AF_NETLINK sockaddr content, Laurent Vivier, 2019/10/22
- [PULL 08/11] linux-user/strace: Add print_sockfd(), Laurent Vivier, 2019/10/22
- [PULL 01/11] linux-user: add strace for dup3, Laurent Vivier, 2019/10/22
- [PULL 11/11] linux-user/syscall: Align target_sockaddr fields using ABI types, Laurent Vivier, 2019/10/22
- [PULL 03/11] linux-user/strace: Display invalid pointer in print_timeval(), Laurent Vivier, 2019/10/22
- [PULL 02/11] Fix unsigned integer underflow in fd-trans.c,
Laurent Vivier <=
- [PULL 09/11] linux-user/strace: Improve bind() output, Laurent Vivier, 2019/10/22
- [PULL 05/11] linux-user/strace: Improve settimeofday(), Laurent Vivier, 2019/10/22
- Re: [PULL 00/11] Linux user for 4.2 patches, Peter Maydell, 2019/10/22