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| author | Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com> | 2019-02-25 20:16:01 +0300 |
|---|---|---|
| committer | Vineet Gupta <vgupta@synopsys.com> | 2019-02-25 12:11:01 -0800 |
| commit | edb64bca50cd736c6894cc6081d5263c007ce005 (patch) | |
| tree | 24677adc79af060445efbc7cfe2f598fee7d1536 /arch | |
| parent | fbe025c3eaf5f52060c2820eddb7357363db0d27 (diff) | |
| download | linux-edb64bca50cd736c6894cc6081d5263c007ce005.tar.gz linux-edb64bca50cd736c6894cc6081d5263c007ce005.tar.bz2 linux-edb64bca50cd736c6894cc6081d5263c007ce005.zip | |
ARC: u-boot args: check that magic number is correct
In case of devboards we really often disable bootloader and load
Linux image in memory via JTAG. Even if kernel tries to verify
uboot_tag and uboot_arg there is sill a chance that we treat some
garbage in registers as valid u-boot arguments in JTAG case.
E.g. it is enough to have '1' in r0 to treat any value in r2 as
a boot command line.
So check that magic number passed from u-boot is correct and drop
u-boot arguments otherwise. That helps to reduce the possibility
of using garbage as u-boot arguments in JTAG case.
We can safely check U-boot magic value (0x0) in linux passed via
r1 register as U-boot pass it from the beginning. So there is no
backward-compatibility issues.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arc/kernel/head.S | 1 | ||||
| -rw-r--r-- | arch/arc/kernel/setup.c | 8 |
2 files changed, 9 insertions, 0 deletions
diff --git a/arch/arc/kernel/head.S b/arch/arc/kernel/head.S index 36774348d23b..8f6e0447dd17 100644 --- a/arch/arc/kernel/head.S +++ b/arch/arc/kernel/head.S @@ -111,6 +111,7 @@ ENTRY(stext) ; r2 = pointer to uboot provided cmdline or external DTB in mem ; These are handled later in handle_uboot_args() st r0, [@uboot_tag] + st r1, [@uboot_magic] st r2, [@uboot_arg] ; setup "current" tsk and optionally cache it in dedicated r25 diff --git a/arch/arc/kernel/setup.c b/arch/arc/kernel/setup.c index 2266e4ee4142..ec2fd231ecd9 100644 --- a/arch/arc/kernel/setup.c +++ b/arch/arc/kernel/setup.c @@ -36,6 +36,7 @@ unsigned int intr_to_DE_cnt; /* Part of U-boot ABI: see head.S */ int __initdata uboot_tag; +int __initdata uboot_magic; char __initdata *uboot_arg; const struct machine_desc *machine_desc; @@ -504,6 +505,8 @@ static inline bool uboot_arg_invalid(unsigned long addr) #define UBOOT_TAG_NONE 0 #define UBOOT_TAG_CMDLINE 1 #define UBOOT_TAG_DTB 2 +/* We always pass 0 as magic from U-boot */ +#define UBOOT_MAGIC_VALUE 0 void __init handle_uboot_args(void) { @@ -518,6 +521,11 @@ void __init handle_uboot_args(void) goto ignore_uboot_args; } + if (uboot_magic != UBOOT_MAGIC_VALUE) { + pr_warn(IGNORE_ARGS "non zero uboot magic\n"); + goto ignore_uboot_args; + } + if (uboot_tag != UBOOT_TAG_NONE && uboot_arg_invalid((unsigned long)uboot_arg)) { pr_warn(IGNORE_ARGS "invalid uboot arg: '%px'\n", uboot_arg); |