linux-user/syscall.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)
The kernel allows a NULL msg in recvfrom so that he size of the next
message may be queried before allocating a correctly sized buffer. This
change allows the syscall translator to pass along the NULL msg pointer
instead of returning early with EFAULT.
Signed-off-by: Zach Reizner <zachr@google.com>
---
v2:
- return -TARGET_EFAULT on non-null invalid msg pointer
linux-user/syscall.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 1e508576c7..294779c86f 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -3679,9 +3679,14 @@ static abi_long do_recvfrom(int fd, abi_ulong
msg, size_t len, int flags,
void *host_msg;
abi_long ret;
- host_msg = lock_user(VERIFY_WRITE, msg, len, 0);
- if (!host_msg)
- return -TARGET_EFAULT;
+ if (!msg) {
+ host_msg = NULL;
+ } else {
+ host_msg = lock_user(VERIFY_WRITE, msg, len, 0);
+ if (!host_msg) {
+ return -TARGET_EFAULT;
+ }
+ }
if (target_addr) {
if (get_user_u32(addrlen, target_addrlen)) {
ret = -TARGET_EFAULT;
--
2.31.0.291.g576ba9dcdaf-goog
Le 27/03/2021 à 03:11, Zach Reizner a écrit : > The kernel allows a NULL msg in recvfrom so that he size of the next > message may be queried before allocating a correctly sized buffer. This > change allows the syscall translator to pass along the NULL msg pointer > instead of returning early with EFAULT. > > Signed-off-by: Zach Reizner <zachr@google.com> > --- > v2: > - return -TARGET_EFAULT on non-null invalid msg pointer > > linux-user/syscall.c | 11 ++++++++--- > 1 file changed, 8 insertions(+), 3 deletions(-) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index 1e508576c7..294779c86f 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -3679,9 +3679,14 @@ static abi_long do_recvfrom(int fd, abi_ulong > msg, size_t len, int flags, > void *host_msg; > abi_long ret; > > - host_msg = lock_user(VERIFY_WRITE, msg, len, 0); > - if (!host_msg) > - return -TARGET_EFAULT; > + if (!msg) { > + host_msg = NULL; > + } else { > + host_msg = lock_user(VERIFY_WRITE, msg, len, 0); > + if (!host_msg) { > + return -TARGET_EFAULT; > + } > + } > if (target_addr) { > if (get_user_u32(addrlen, target_addrlen)) { > ret = -TARGET_EFAULT; > Reviewed-by: Laurent Vivier <laurent@vivier.eu>
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