From 54841ab50c20d6fa6c9cc3eb826989da3a22d934 Mon Sep 17 00:00:00 2001 From: Wolfgang Denk Date: Mon, 28 Jun 2010 22:00:46 +0200 Subject: Make sure that argv[] argument pointers are not modified. The hush shell dynamically allocates (and re-allocates) memory for the argument strings in the "char *argv[]" argument vector passed to commands. Any code that modifies these pointers will cause serious corruption of the malloc data structures and crash U-Boot, so make sure the compiler can check that no such modifications are being done by changing the code into "char * const argv[]". This modification is the result of debugging a strange crash caused after adding a new command, which used the following argument processing code which has been working perfectly fine in all Unix systems since version 6 - but not so in U-Boot: int main (int argc, char **argv) { while (--argc > 0 && **++argv == '-') { /* ====> */ while (*++*argv) { switch (**argv) { case 'd': debug++; break; ... default: usage (); } } } ... } The line marked "====>" will corrupt the malloc data structures and usually cause U-Boot to crash when the next command gets executed by the shell. With the modification, the compiler will prevent this with an error: increment of read-only location '*argv' N.B.: The code above can be trivially rewritten like this: while (--argc > 0 && **++argv == '-') { char *arg = *argv; while (*++arg) { switch (*arg) { ... Signed-off-by: Wolfgang Denk Acked-by: Mike Frysinger --- common/cmd_dcr.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'common/cmd_dcr.c') diff --git a/common/cmd_dcr.c b/common/cmd_dcr.c index 4f23b8d5911..45de8cd65a8 100644 --- a/common/cmd_dcr.c +++ b/common/cmd_dcr.c @@ -36,7 +36,7 @@ unsigned long set_dcr (unsigned short, unsigned long); * Interpreter command to retrieve an AMCC PPC 4xx Device Control Register * ======================================================================= */ -int do_getdcr ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[] ) +int do_getdcr ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[] ) { unsigned short dcrn; /* Device Control Register Num */ unsigned long value; /* DCR's value */ @@ -63,7 +63,7 @@ int do_getdcr ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[] ) * Interpreter command to set an AMCC PPC 4xx Device Control Register * ====================================================================== */ -int do_setdcr (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_setdcr (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { unsigned short dcrn; /* Device Control Register Num */ unsigned long value; @@ -110,7 +110,7 @@ int do_setdcr (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) * Device Control Register inderect addressing. * ======================================================================= */ -int do_getidcr (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_getidcr (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { unsigned short adr_dcrn; /* Device Control Register Num for Address */ unsigned short dat_dcrn; /* Device Control Register Num for Data */ @@ -166,7 +166,7 @@ int do_getidcr (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) * Device Control Register inderect addressing. * ======================================================================= */ -int do_setidcr (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_setidcr (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { unsigned short adr_dcrn; /* Device Control Register Num for Address */ unsigned short dat_dcrn; /* Device Control Register Num for Data */ -- cgit v1.2.3