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Date: Sun, 26 Mar 2023 21:12:41 +0000
From: ca0 <ca0@...tonmail.ch>
To: "musl@...ts.openwall.com" <musl@...ts.openwall.com>
Subject: socketcall syscall on x32 ABI producing incorrect results
I am running busybox with musl-1.2.3 on x32 linux with gcc-12.2.0.
The syscall returns bad address in the case of the bind call. I have traced this down to the pointer being 0xf...... in 32bits being sign extended to 32bits in the syscall.
Here is the code:
0xf7f687ec 65 else r = __syscall(sys, a, b, c, d, e, f);
0xf7f687e9 <__alt_socketcall+178>: 48 63 d0 movslq %eax,%rdx
I can see the address being sign extended as intended by the movslq instruction.
If I change the bind implementation to cast this address I do not see this issue, but other issues arise with the soecket call
ie. in bind
int bind(int fd, const struct sockaddr *addr, socklen_t len)
{
long b = ((unsigned long)(addr) & 0xffffffff);
freturn socketcall(bind, fd, b, len, 0, 0, 0);
}
Is this a known issue as x32 is marked as experimental.
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