[PATCH v6] crash: Fix crash memory reserve exceed system memory bug

[Jinjie Ruan]

On x86_32 Qemu machine with 1GB memory, the cmdline "crashkernel=4G" is ok
as below:
	crashkernel reserved: 0x0000000020000000 - 0x0000000120000000 (4096 MB)

It's similar on other architectures, such as ARM32 and RISCV32.

The cause is that the crash_size is parsed and printed with "unsigned long
long" data type which is 8 bytes but allocated used with "phys_addr_t"
which is 4 bytes in memblock_phys_alloc_range().

Fix it by checking if crash_size is greater than system RAM size and
return error if so.

After this patch, there is no above confusing reserve success info.

Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
Suggested-by: Mike Rapoport <rppt@xxxxxxxxxx>
Acked-by: Baoquan He <bhe@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
v6:
- Take off Baoquan's Suggested-by.
v5:
- Fix it in common parse_crashkernel() instead of per-arch.
- Add suggested-by.

v4:
- Update the warn info to align with parse_crashkernel_mem().
- Rebased on the "ARM: Use generic interface to simplify crashkernel
  reservation" patch.
- Also fix for riscv32.
- Update the commit message.

v3:
- Handle the check in reserve_crashkernel() Baoquan suggested.
- Split x86_32 and arm32.
- Add Suggested-by.
- Drop the wrong fix tag.

v2:
- Also fix for x86_32.
- Update the fix method.
- Peel off the other two patches.
- Update the commit message.
---
 kernel/crash_reserve.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c
index ad5b3f2c5487..5387269114f6 100644
--- a/kernel/crash_reserve.c
+++ b/kernel/crash_reserve.c
@@ -335,6 +335,9 @@ int __init parse_crashkernel(char *cmdline,
 	if (!*crash_size)
 		ret = -EINVAL;
 
+	if (*crash_size >= system_ram)
+		ret = -EINVAL;
+
 	return ret;
 }
 
-- 
2.34.1