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author | Wolfgang Denk <wd@denx.de> | 2010-06-28 22:00:46 +0200 |
---|---|---|
committer | Wolfgang Denk <wd@denx.de> | 2010-07-04 23:55:42 +0200 |
commit | 54841ab50c20d6fa6c9cc3eb826989da3a22d934 (patch) | |
tree | 400f22f0a12ff0ae6c472bed6ac648befc1744a2 /common/cmd_ext2.c | |
parent | b218ccb5435e64ac2318bb8b6c9594ef1cc724cd (diff) | |
download | u-boot-54841ab50c20d6fa6c9cc3eb826989da3a22d934.zip u-boot-54841ab50c20d6fa6c9cc3eb826989da3a22d934.tar.gz u-boot-54841ab50c20d6fa6c9cc3eb826989da3a22d934.tar.bz2 |
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 <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Diffstat (limited to 'common/cmd_ext2.c')
-rw-r--r-- | common/cmd_ext2.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/common/cmd_ext2.c b/common/cmd_ext2.c index b7e4048..49021cd 100644 --- a/common/cmd_ext2.c +++ b/common/cmd_ext2.c @@ -56,7 +56,7 @@ #define PRINTF(fmt,args...) #endif -int do_ext2ls (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_ext2ls (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { char *filename = "/"; int dev=0; @@ -123,7 +123,7 @@ U_BOOT_CMD( /****************************************************************************** * Ext2fs boot command intepreter. Derived from diskboot */ -int do_ext2load (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_ext2load (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { char *filename = NULL; char *ep; |