From: Prasad J Pandit <p...@fedoraproject.org> Limit the number of arguments passed to execve(2) call from a user program, as large number of them could lead to a bad guest address error.
Reported-by: Jann Horn <ja...@google.com> Signed-off-by: Prasad J Pandit <p...@fedoraproject.org> --- linux-user/syscall.c | 6 ++++++ 1 file changed, 6 insertions(+) Update per: use gemu_log() to report error -> https://lists.gnu.org/archive/html/qemu-devel/2017-03/msg00750.html diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 9be8e95..86a4a9c 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -7766,6 +7766,7 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, #endif case TARGET_NR_execve: { +#define ARG_MAX 65535 char **argp, **envp; int argc, envc; abi_ulong gp; @@ -7794,6 +7795,11 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, envc++; } + if (argc > ARG_MAX || envc > ARG_MAX) { + gemu_log("argc(%d), envc(%d) exceed %d\n", argc, envc, ARG_MAX); + ret = -TARGET_E2BIG; + break; + } argp = alloca((argc + 1) * sizeof(void *)); envp = alloca((envc + 1) * sizeof(void *)); -- 2.9.3
