From a6f79cc9a5efc34c5b751b2e866a4977259f3f63 Mon Sep 17 00:00:00 2001 From: Ulrich Hecht Date: Tue, 31 Jan 2012 12:43:16 +0100 Subject: linux-user: fail execve() if env/args too big If the host's page size is equal to or smaller than the target's, native execve() will fail appropriately with E2BIG if called with too big an environment for the target to handle. It may falsely succeed, however, if the host's page size is bigger, and feed the executed target process an environment that is too big for it to handle, at which point QEMU barfs and exits, confusing procmail's autoconf script and causing the build to fail. This patch makes sure that execve() will return E2BIG if the environment is too large for the target. Signed-off-by: Ulrich Hecht Signed-off-by: Stefan Hajnoczi --- linux-user/syscall.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index ee8899ef3d..e868ec6aff 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -4949,6 +4949,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, abi_ulong guest_envp; abi_ulong addr; char **q; + int total_size = 0; argc = 0; guest_argp = arg2; @@ -4980,6 +4981,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, break; if (!(*q = lock_user_string(addr))) goto execve_efault; + total_size += strlen(*q) + 1; } *q = NULL; @@ -4991,9 +4993,16 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, break; if (!(*q = lock_user_string(addr))) goto execve_efault; + total_size += strlen(*q) + 1; } *q = NULL; + /* This case will not be caught by the host's execve() if its + page size is bigger than the target's. */ + if (total_size > MAX_ARG_PAGES * TARGET_PAGE_SIZE) { + ret = -TARGET_E2BIG; + goto execve_end; + } if (!(p = lock_user_string(arg1))) goto execve_efault; ret = get_errno(execve(p, argp, envp)); -- cgit v1.2.1