The code assumed that when strol is successful, that it will set errno to zero. This is not the case, at least under uClinux. The man page does not indicate this either. What can happen is that errno is already set to non-zero before strol is called, then strol is successful but since strol doesn't reset errno to zero, the next line thinks that strol failed.
This patch also gets rid of 2 compiler warnings. diff -up ../../dropbear-vanilla/dropbear-0.51/cli-runopts.c ../../dropbear-errno/dropbear-0.51/cli-runopts.c --- ../../dropbear-vanilla/dropbear-0.51/cli-runopts.c 2008-03-27 09:17:14.000000000 -0400 +++ ../../dropbear-errno/dropbear-0.51/cli-runopts.c 2008-09-19 16:26:36.000000000 -0400 @@ -428,12 +428,14 @@ static void addforward(char* origstr, st /* Now we check the ports - note that the port ints are unsigned, * the check later only checks for >= MAX_PORT */ + errno = 0; newfwd->listenport = strtol(listenport, NULL, 10); if (errno != 0) { TRACE(("bad listenport strtol")) goto fail; } + errno = 0; newfwd->connectport = strtol(connectport, NULL, 10); if (errno != 0) { TRACE(("bad connectport strtol")) Common subdirectories: ../../dropbear-vanilla/dropbear-0.51/debian and ../../dropbear-errno/dropbear-0.51/debian diff -up ../../dropbear-vanilla/dropbear-0.51/keyimport.c ../../dropbear-errno/dropbear-0.51/keyimport.c --- ../../dropbear-vanilla/dropbear-0.51/keyimport.c 2008-03-27 09:17:14.000000000 -0400 +++ ../../dropbear-errno/dropbear-0.51/keyimport.c 2008-09-19 16:39:08.000000000 -0400 @@ -701,7 +701,6 @@ static int openssh_write(const char *fil int nnumbers = -1, pos, len, seqlen, i; char *header = NULL, *footer = NULL; char zero[1]; - unsigned char iv[8]; int ret = 0; FILE *fp; int keytype = -1; Common subdirectories: ../../dropbear-vanilla/dropbear-0.51/libtomcrypt and ../../dropbear-errno/dropbear-0.51/libtomcrypt Common subdirectories: ../../dropbear-vanilla/dropbear-0.51/libtommath and ../../dropbear-errno/dropbear-0.51/libtommath Common subdirectories: ../../dropbear-vanilla/dropbear-0.51/_MTN and ../../dropbear-errno/dropbear-0.51/_MTN Only in ../../dropbear-errno/dropbear-0.51: patch051.errno diff -up ../../dropbear-vanilla/dropbear-0.51/svr-auth.c ../../dropbear-errno/dropbear-0.51/svr-auth.c --- ../../dropbear-vanilla/dropbear-0.51/svr-auth.c 2008-03-27 09:17:16.000000000 -0400 +++ ../../dropbear-errno/dropbear-0.51/svr-auth.c 2008-09-19 16:38:58.000000000 -0400 @@ -203,7 +203,7 @@ out: m_free(methodname); } -static int fill_passwd(const char* username) { +static void fill_passwd(const char* username) { struct passwd *pw = NULL; if (ses.authstate.pw_name) m_free(ses.authstate.pw_name);