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linux-user: allow NULL msg in recvfrom

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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>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <CAFNex=DvFCq=AQf+=19fTfw-T8eZZT=3NnFFm2JMFvVr5QgQyA@mail.gmail.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>
This commit is contained in:
Zach Reizner 2021-03-26 22:11:16 -04:00 committed by Laurent Vivier
parent 23fff7a17f
commit 4a1e6bce23
1 changed files with 8 additions and 3 deletions
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11
linux-user/syscall.c
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@ -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;