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authorJonathan Neuschäfer <j.neuschaefer@gmx.net>2015-09-03 07:27:26 +0200
committerRiku Voipio <riku.voipio@linaro.org>2015-09-28 16:39:43 +0300
commitee1045877a7e226945c7cec2bda80039bd2d0c8e (patch)
tree00161e36d739a5ccfb44e26d25f1708bb1ddc9ab
parent59baae9a626396a3a05840279084c4bf2beb8f40 (diff)
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>
-rw-r--r--linux-user/syscall.c14
-rw-r--r--linux-user/syscall_defs.h14
2 files changed, 18 insertions, 10 deletions
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 7fbaa8bb67..75ac32c05d 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -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:
diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
index cdc8db421c..7ca33a6f62 100644
--- a/linux-user/syscall_defs.h
+++ b/linux-user/syscall_defs.h
@@ -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 {