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[Qemu-devel] [PATCH] linux-user: ioctl() command type is int

From: Laurent Vivier
Subject: [Qemu-devel] [PATCH] linux-user: ioctl() command type is int
Date: Fri, 22 May 2015 00:18:57 +0200

When executing a 64bit target chroot on 64bit host,
the ioctl() command can mismatch.

It seems the previous commit doesn't solve the problem in
my case:

        9c6bf9c7 linux-user: Fix ioctl cmd type mismatch on 64-bit targets

For example, a ppc64 chroot on an x86_64 host:

bash-4.3# ls
Unsupported ioctl: cmd=0x80087467
Unsupported ioctl: cmd=0x802c7415

The origin of the problem is in syscall.c:do_ioctl().

        static abi_long do_ioctl(int fd, abi_long cmd, abi_long arg)

In this case (ppc64) abi_long is long (on the x86_64), and

    cmd = 0x0000000080087467

        if (ie->target_cmd == cmd)

target_cmd is int, so target_cmd = 0x80087467
and to compare an int with a long, the sign is extended to 64bit,
so the comparison is:

        if (0xffffffff80087467 == 0x0000000080087467)

which doesn't match whereas it should.

This patch uses abi_int in the case of the target command type
instead of abi_long (and for consistency, update IOCTLEntry).

Signed-off-by: Laurent Vivier <address@hidden>
 linux-user/syscall.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 1622ad6..68801cf 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -3293,8 +3293,8 @@ typedef abi_long do_ioctl_fn(const IOCTLEntry *ie, 
uint8_t *buf_temp,
                              int fd, abi_long cmd, abi_long arg);
 struct IOCTLEntry {
-    int target_cmd;
-    unsigned int host_cmd;
+    abi_int target_cmd;
+    int host_cmd;
     const char *name;
     int access;
     do_ioctl_fn *do_ioctl;
@@ -3849,7 +3849,7 @@ static IOCTLEntry ioctl_entries[] = {
 /* ??? Implement proper locking for ioctls.  */
 /* do_ioctl() Must return target values and target errnos. */
-static abi_long do_ioctl(int fd, abi_long cmd, abi_long arg)
+static abi_long do_ioctl(int fd, abi_int cmd, abi_long arg)
     const IOCTLEntry *ie;
     const argtype *arg_type;

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