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authorWolfgang Denk <wd@denx.de>2010-06-28 22:00:46 +0200
committerWolfgang Denk <wd@denx.de>2010-07-04 23:55:42 +0200
commit54841ab50c20d6fa6c9cc3eb826989da3a22d934 (patch)
tree400f22f0a12ff0ae6c472bed6ac648befc1744a2 /board/lwmon5/kbd.c
parentb218ccb5435e64ac2318bb8b6c9594ef1cc724cd (diff)
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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 'board/lwmon5/kbd.c')
-rw-r--r--board/lwmon5/kbd.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/board/lwmon5/kbd.c b/board/lwmon5/kbd.c
index be1a1df..0e26b89 100644
--- a/board/lwmon5/kbd.c
+++ b/board/lwmon5/kbd.c
@@ -380,7 +380,7 @@ static uchar *key_match (uchar *kbd_data)
/***********************************************************************
F* Function: int do_kbd (cmd_tbl_t *cmdtp, int flag,
-F* int argc, char *argv[]) P*A*Z*
+F* int argc, char * const argv[]) P*A*Z*
*
P* Parameters: cmd_tbl_t *cmdtp
P* - Pointer to our command table entry
@@ -389,7 +389,7 @@ P* - If the CMD_FLAG_REPEAT bit is set, then this call is
P* a repetition
P* int argc
P* - Argument count
-P* char *argv[]
+P* char * const argv[]
P* - Array of the actual arguments
P*
P* Returnvalue: int
@@ -404,7 +404,7 @@ D* Design: wd@denx.de
C* Coding: wd@denx.de
V* Verification: dzu@denx.de
***********************************************************************/
-int do_kbd (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_kbd (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
uchar kbd_data[KEYBD_DATALEN];
char keybd_env[2 * KEYBD_DATALEN + 1];