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/image.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'common/image.c') diff --git a/common/image.c b/common/image.c index 2b6007e..6d8833e 100644 --- a/common/image.c +++ b/common/image.c @@ -60,7 +60,7 @@ static int fit_check_ramdisk (const void *fit, int os_noffset, #endif #ifdef CONFIG_CMD_BDI -extern int do_bdinfo(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]); +extern int do_bdinfo(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]); #endif DECLARE_GLOBAL_DATA_PTR; @@ -756,7 +756,7 @@ int genimg_has_config (bootm_headers_t *images) * 1, if ramdisk image is found but corrupted, or invalid * rd_start and rd_end are set to 0 if no ramdisk exists */ -int boot_get_ramdisk (int argc, char *argv[], bootm_headers_t *images, +int boot_get_ramdisk (int argc, char * const argv[], bootm_headers_t *images, uint8_t arch, ulong *rd_start, ulong *rd_end) { ulong rd_addr, rd_load; @@ -1279,7 +1279,7 @@ error: * 1, if fdt image is found but corrupted * of_flat_tree and of_size are set to 0 if no fdt exists */ -int boot_get_fdt (int flag, int argc, char *argv[], bootm_headers_t *images, +int boot_get_fdt (int flag, int argc, char * const argv[], bootm_headers_t *images, char **of_flat_tree, ulong *of_size) { const image_header_t *fdt_hdr; -- cgit v1.1