From 33cddf77974f9849cf8edafe9b3da46591b73d6e Mon Sep 17 00:00:00 2001 From: Takashi Yano Date: Mon, 28 Aug 2023 22:14:41 +0900 Subject: Cygwin: Fix segfalt when too many command line args are specified. Previously, the number of command line args was not checked for cygwin process. Due to this, segmentation fault was caused if too many command line args are specified. https://cygwin.com/pipermail/cygwin/2023-August/254333.html Since char *argv[argc + 1] is placed on the stack in dll_crt0_1(), STATUS_STACK_OVERFLOW occurs if the stack does not have enough space. With this patch, char *argv[] is placed in heap instead of stack and ARG_MAX is increased from 32000 to 2097152 which is default value of Linux. The argument length is also compared with ARG_MAX and spawnve() returns E2BIG if it is too long. Reported-by: Ed Morton Reviewed-by: Corinna Vinschen Signed-off-by: Takashi Yano --- winsup/cygwin/dcrt0.cc | 7 ++----- winsup/cygwin/local_includes/winsup.h | 4 ++++ winsup/cygwin/release/3.4.9 | 3 +++ winsup/cygwin/spawn.cc | 9 ++++++++- winsup/cygwin/sysconf.cc | 2 +- 5 files changed, 18 insertions(+), 7 deletions(-) diff --git a/winsup/cygwin/dcrt0.cc b/winsup/cygwin/dcrt0.cc index 49b7a44..1d88105 100644 --- a/winsup/cygwin/dcrt0.cc +++ b/winsup/cygwin/dcrt0.cc @@ -978,11 +978,8 @@ dll_crt0_1 (void *) a change to an element of argv[] it does not affect Cygwin's argv. Changing the the contents of what argv[n] points to will still affect Cygwin. This is similar (but not exactly like) Linux. */ - char *newargv[__argc + 1]; - char **nav = newargv; - char **oav = __argv; - while ((*nav++ = *oav++) != NULL) - continue; + char **newargv = (char **) malloc ((__argc + 1) * sizeof (char *)); + memcpy (newargv, __argv, (__argc + 1) * sizeof (char *)); /* Handle any signals which may have arrived */ sig_dispatch_pending (false); _my_tls.call_signal_handler (); diff --git a/winsup/cygwin/local_includes/winsup.h b/winsup/cygwin/local_includes/winsup.h index 43dfbf4..2d51722 100644 --- a/winsup/cygwin/local_includes/winsup.h +++ b/winsup/cygwin/local_includes/winsup.h @@ -68,6 +68,10 @@ uint32_t cygwin_inet_addr (const char *cp); application provided path strings we handle. */ #define NT_MAX_PATH 32768 +/* CYG_ARG_MAX is the maximum total length of command line args. + The value 2097152 is the default ARG_MAX value in Linux. */ +#define CYG_ARG_MAX 2097152 + /* This definition allows to define wide char strings using macros as parameters. See the definition of __CONCAT in newlib's sys/cdefs.h and accompanying comment. */ diff --git a/winsup/cygwin/release/3.4.9 b/winsup/cygwin/release/3.4.9 index 2f2da9e..53c4e5f 100644 --- a/winsup/cygwin/release/3.4.9 +++ b/winsup/cygwin/release/3.4.9 @@ -8,3 +8,6 @@ Bug Fixes - For the time being, disable creating special files using mknod/mkfifo on NFS. Addresses: https://cygwin.com/pipermail/cygwin/2023-August/254266.html + +- Fix segfault when too many command line args are specified. + Addresses: https://cygwin.com/pipermail/cygwin/2023-August/254333.html diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc index 32ba5b3..c4888e8 100644 --- a/winsup/cygwin/spawn.cc +++ b/winsup/cygwin/spawn.cc @@ -340,8 +340,9 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv, We need to quote any argument that has whitespace or embedded "'s. */ int ac; + size_t arg_len = 0; for (ac = 0; argv[ac]; ac++) - /* nothing */; + arg_len += strlen (argv[ac]) + 1; int err; const char *ext; @@ -510,6 +511,12 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv, __leave; } set (chtype, real_path.iscygexec ()); + if (iscygwin () && arg_len > (size_t) sysconf (_SC_ARG_MAX)) + { + set_errno (E2BIG); + res = -1; + __leave; + } __stdin = in__stdin; __stdout = in__stdout; record_children (); diff --git a/winsup/cygwin/sysconf.cc b/winsup/cygwin/sysconf.cc index 2db92e4..7cdfbdb 100644 --- a/winsup/cygwin/sysconf.cc +++ b/winsup/cygwin/sysconf.cc @@ -485,7 +485,7 @@ static struct }; } sca[] = { - {cons, {c:ARG_MAX}}, /* 0, _SC_ARG_MAX */ + {cons, {c:CYG_ARG_MAX}}, /* 0, _SC_ARG_MAX */ {cons, {c:CHILD_MAX}}, /* 1, _SC_CHILD_MAX */ {cons, {c:CLOCKS_PER_SEC}}, /* 2, _SC_CLK_TCK */ {cons, {c:NGROUPS_MAX}}, /* 3, _SC_NGROUPS_MAX */ -- cgit v1.1