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_fdt.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'common/cmd_fdt.c') diff --git a/common/cmd_fdt.c b/common/cmd_fdt.c index 5df79ae3e1..cd4c6de6da 100644 --- a/common/cmd_fdt.c +++ b/common/cmd_fdt.c @@ -42,7 +42,7 @@ DECLARE_GLOBAL_DATA_PTR; static int fdt_valid(void); -static int fdt_parse_prop(char **newval, int count, char *data, int *len); +static int fdt_parse_prop(char *const*newval, int count, char *data, int *len); static int fdt_print(const char *pathp, char *prop, int depth); /* @@ -63,7 +63,7 @@ void set_working_fdt_addr(void *addr) /* * Flattened Device Tree command, see the help for parameter definitions. */ -int do_fdt (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_fdt (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { if (argc < 2) { cmd_usage(cmdtp); @@ -515,7 +515,7 @@ static int fdt_valid(void) * data: A bytestream to be placed in the property * len: The length of the resulting bytestream */ -static int fdt_parse_prop(char **newval, int count, char *data, int *len) +static int fdt_parse_prop(char * const *newval, int count, char *data, int *len) { char *cp; /* temporary char pointer */ char *newp; /* temporary newval char pointer */ -- cgit v1.2.1