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_bmp.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'common/cmd_bmp.c') diff --git a/common/cmd_bmp.c b/common/cmd_bmp.c index 583b0090c..5ec798c54 100644 --- a/common/cmd_bmp.c +++ b/common/cmd_bmp.c @@ -90,7 +90,7 @@ bmp_image_t *gunzip_bmp(unsigned long addr, unsigned long *lenp) } #endif -static int do_bmp_info(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +static int do_bmp_info(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { ulong addr; @@ -109,7 +109,7 @@ static int do_bmp_info(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) return (bmp_info(addr)); } -static int do_bmp_display(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +static int do_bmp_display(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { ulong addr; int x = 0, y = 0; @@ -149,7 +149,7 @@ static cmd_tbl_t cmd_bmp_sub[] = { * Return: None * */ -static int do_bmp(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +static int do_bmp(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { cmd_tbl_t *c; -- cgit v1.2.3-70-g09d2