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_bedbug.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) (limited to 'common/cmd_bedbug.c') diff --git a/common/cmd_bedbug.c b/common/cmd_bedbug.c index 8be1c25fd7..d01ee19ee5 100644 --- a/common/cmd_bedbug.c +++ b/common/cmd_bedbug.c @@ -73,7 +73,7 @@ void bedbug_init (void) * Entry point from the interpreter to the disassembler. Repeated calls * will resume from the last disassembled address. * ====================================================================== */ -int do_bedbug_dis (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_bedbug_dis (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { ulong addr; /* Address to start disassembly from */ ulong len; /* # of instructions to disassemble */ @@ -115,7 +115,7 @@ U_BOOT_CMD (ds, 3, 1, do_bedbug_dis, * instructions in consecutive memory locations until a '.' (period) is * entered on a line by itself. * ====================================================================== */ -int do_bedbug_asm (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_bedbug_asm (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { long mem_addr; /* Address to assemble into */ unsigned long instr; /* Machine code for text */ @@ -167,7 +167,7 @@ U_BOOT_CMD (as, 2, 0, do_bedbug_asm, * CPU-specific break point set routine. * ====================================================================== */ -int do_bedbug_break (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_bedbug_break (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { /* -------------------------------------------------- */ if (bug_ctx.do_break) @@ -263,7 +263,7 @@ void bedbug_main_loop (unsigned long addr, struct pt_regs *regs) * stopped flag in the context so that the breakpoint routine will * return. * ====================================================================== */ -int do_bedbug_continue (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_bedbug_continue (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { /* -------------------------------------------------- */ @@ -286,7 +286,7 @@ U_BOOT_CMD (continue, 1, 0, do_bedbug_continue, * the address passes control to the CPU-specific set breakpoint routine * for the current breakpoint number. * ====================================================================== */ -int do_bedbug_step (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_bedbug_step (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { unsigned long addr; /* Address to stop at */ @@ -317,7 +317,7 @@ U_BOOT_CMD (step, 1, 1, do_bedbug_step, * the address passes control to the CPU-specific set breakpoint routine * for the current breakpoint number. * ====================================================================== */ -int do_bedbug_next (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_bedbug_next (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { unsigned long addr; /* Address to stop at */ @@ -346,7 +346,7 @@ U_BOOT_CMD (next, 1, 1, do_bedbug_next, * Interpreter command to print the current stack. This assumes an EABI * architecture, so it starts with GPR R1 and works back up the stack. * ====================================================================== */ -int do_bedbug_stack (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_bedbug_stack (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { unsigned long sp; /* Stack pointer */ unsigned long func; /* LR from stack */ @@ -391,7 +391,7 @@ U_BOOT_CMD (where, 1, 1, do_bedbug_stack, * Interpreter command to dump the registers. Calls the CPU-specific * show registers routine. * ====================================================================== */ -int do_bedbug_rdump (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_bedbug_rdump (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { /* -------------------------------------------------- */ -- cgit v1.2.3