From ee1045877a7e226945c7cec2bda80039bd2d0c8e Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jonathan=20Neusch=C3=A4fer?= Date: Thu, 3 Sep 2015 07:27:26 +0200 Subject: [PATCH] linux-user: fix cmsg conversion in case of multiple headers MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Jonathan Neuschäfer Signed-off-by: Riku Voipio --- linux-user/syscall.c | 14 +++++++++----- linux-user/syscall_defs.h | 14 +++++++++----- 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 {