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_fat.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'common/cmd_fat.c') diff --git a/common/cmd_fat.c b/common/cmd_fat.c index f3089a296e..ede730804e 100644 --- a/common/cmd_fat.c +++ b/common/cmd_fat.c @@ -33,7 +33,7 @@ #include -int do_fat_fsload (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_fat_fsload (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { long size; unsigned long offset; @@ -94,7 +94,7 @@ U_BOOT_CMD( " to address 'addr' from dos filesystem" ); -int do_fat_ls (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_fat_ls (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { char *filename = "/"; int ret; @@ -141,7 +141,7 @@ U_BOOT_CMD( " - list files from 'dev' on 'interface' in a 'directory'" ); -int do_fat_fsinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_fat_fsinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { int dev=0; int part=1; @@ -227,7 +227,7 @@ int find_fat_partition (void) } int -do_fat_dump (cmd_tbl_t *cmdtp, bd_t *bd, int flag, int argc, char *argv[]) +do_fat_dump (cmd_tbl_t *cmdtp, bd_t *bd, int flag, int argc, char * const argv[]) { __u8 block[1024]; int ret; -- cgit v1.2.1