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linux-user: fix cmsg conversion in case of multiple headers 

Currently, __target_cmsg_nxthdr compares a pointer derived from
target_cmsg against the msg_control field of target_msgh (through
subtraction).  This failed for me when emulating i386 code under x86_64,
because pointers in the host address space and pointers in the guest
address space were not the same.  This patch passes the initial value of
target_cmsg into __target_cmsg_nxthdr.

I found and fixed two more related bugs:
- __target_cmsg_nxthdr now returns the new cmsg pointer instead of the
  old one.
- tgt_space (in host_to_target_cmsg) doesn't count "sizeof (struct
  target_cmsghdr)" twice anymore.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Jonathan Neuschäfer <j.neuschaefer@gmx.net>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
This commit is contained in:
Jonathan Neuschäfer 2015-09-03 07:27:26 +02:00 committed by Riku Voipio
parent 59baae9a62
commit ee1045877a
2 changed files with 18 additions and 10 deletions
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14
linux-user/syscall.c
View File

@ -1181,7 +1181,7 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
struct cmsghdr *cmsg = CMSG_FIRSTHDR(msgh);
abi_long msg_controllen;
abi_ulong target_cmsg_addr;
struct target_cmsghdr *target_cmsg;
struct target_cmsghdr *target_cmsg, *target_cmsg_start;
socklen_t space = 0;
msg_controllen = tswapal(target_msgh->msg_controllen);
@ -1189,6 +1189,7 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
goto the_end;
target_cmsg_addr = tswapal(target_msgh->msg_control);
target_cmsg = lock_user(VERIFY_READ, target_cmsg_addr, msg_controllen, 1);
target_cmsg_start = target_cmsg;
if (!target_cmsg)
return -TARGET_EFAULT;
@ -1247,7 +1248,8 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
}
cmsg = CMSG_NXTHDR(msgh, cmsg);
target_cmsg = TARGET_CMSG_NXTHDR(target_msgh, target_cmsg);
target_cmsg = TARGET_CMSG_NXTHDR(target_msgh, target_cmsg,
target_cmsg_start);
}
unlock_user(target_cmsg, target_cmsg_addr, 0);
the_end:
@ -1261,7 +1263,7 @@ static inline abi_long host_to_target_cmsg(struct target_msghdr *target_msgh,
struct cmsghdr *cmsg = CMSG_FIRSTHDR(msgh);
abi_long msg_controllen;
abi_ulong target_cmsg_addr;
struct target_cmsghdr *target_cmsg;
struct target_cmsghdr *target_cmsg, *target_cmsg_start;
socklen_t space = 0;
msg_controllen = tswapal(target_msgh->msg_controllen);
@ -1269,6 +1271,7 @@ static inline abi_long host_to_target_cmsg(struct target_msghdr *target_msgh,
goto the_end;
target_cmsg_addr = tswapal(target_msgh->msg_control);
target_cmsg = lock_user(VERIFY_WRITE, target_cmsg_addr, msg_controllen, 0);
target_cmsg_start = target_cmsg;
if (!target_cmsg)
return -TARGET_EFAULT;
@ -1382,14 +1385,15 @@ static inline abi_long host_to_target_cmsg(struct target_msghdr *target_msgh,
}
target_cmsg->cmsg_len = tswapal(tgt_len);
tgt_space = TARGET_CMSG_SPACE(tgt_len);
tgt_space = TARGET_CMSG_SPACE(len);
if (msg_controllen < tgt_space) {
tgt_space = msg_controllen;
}
msg_controllen -= tgt_space;
space += tgt_space;
cmsg = CMSG_NXTHDR(msgh, cmsg);
target_cmsg = TARGET_CMSG_NXTHDR(target_msgh, target_cmsg);
target_cmsg = TARGET_CMSG_NXTHDR(target_msgh, target_cmsg,
target_cmsg_start);
}
unlock_user(target_cmsg, target_cmsg_addr, space);
the_end:

14
linux-user/syscall_defs.h
View File

@ -235,7 +235,8 @@ struct target_cmsghdr {
};
#define TARGET_CMSG_DATA(cmsg) ((unsigned char *) ((struct target_cmsghdr *) (cmsg) + 1))
#define TARGET_CMSG_NXTHDR(mhdr, cmsg) __target_cmsg_nxthdr (mhdr, cmsg)
#define TARGET_CMSG_NXTHDR(mhdr, cmsg, cmsg_start) \
__target_cmsg_nxthdr(mhdr, cmsg, cmsg_start)
#define TARGET_CMSG_ALIGN(len) (((len) + sizeof (abi_long) - 1) \
& (size_t) ~(sizeof (abi_long) - 1))
#define TARGET_CMSG_SPACE(len) (TARGET_CMSG_ALIGN (len) \
@ -243,17 +244,20 @@ struct target_cmsghdr {
#define TARGET_CMSG_LEN(len) (TARGET_CMSG_ALIGN (sizeof (struct target_cmsghdr)) + (len))
static __inline__ struct target_cmsghdr *
__target_cmsg_nxthdr (struct target_msghdr *__mhdr, struct target_cmsghdr *__cmsg)
__target_cmsg_nxthdr(struct target_msghdr *__mhdr,
struct target_cmsghdr *__cmsg,
struct target_cmsghdr *__cmsg_start)
{
struct target_cmsghdr *__ptr;
__ptr = (struct target_cmsghdr *)((unsigned char *) __cmsg
+ TARGET_CMSG_ALIGN (tswapal(__cmsg->cmsg_len)));
if ((unsigned long)((char *)(__ptr+1) - (char *)(size_t)tswapal(__mhdr->msg_control))
> tswapal(__mhdr->msg_controllen))
if ((unsigned long)((char *)(__ptr+1) - (char *)__cmsg_start)
> tswapal(__mhdr->msg_controllen)) {
/* No more entries. */
return (struct target_cmsghdr *)0;
return __cmsg;
}
return __ptr;
}
struct target_mmsghdr {