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_nand.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'common/cmd_nand.c') diff --git a/common/cmd_nand.c b/common/cmd_nand.c index f611fd7717..ea80555ef8 100644 --- a/common/cmd_nand.c +++ b/common/cmd_nand.c @@ -90,7 +90,7 @@ static inline int str2long(char *p, ulong *num) } static int -arg_off_size(int argc, char *argv[], nand_info_t *nand, ulong *off, size_t *size) +arg_off_size(int argc, char * const argv[], nand_info_t *nand, ulong *off, size_t *size) { int idx = nand_curr_device; #if defined(CONFIG_CMD_MTDPARTS) @@ -204,7 +204,7 @@ static void nand_print_info(int idx) nand->name, nand->erasesize >> 10); } -int do_nand(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_nand(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { int i, dev, ret = 0; ulong addr, off; @@ -599,7 +599,7 @@ static int nand_load_image(cmd_tbl_t *cmdtp, nand_info_t *nand, return 0; } -int do_nandboot(cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_nandboot(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { char *boot_device = NULL; int idx; -- cgit v1.2.1