Hi again Chris,
On 04/23/2020 05:29 AM, Christophe Leroy wrote:
Hi,
Christophe
Le 23/04/2020 à 03:13, Chris Packham a écrit :
Hi,
I'm just in the process of updating our products to Linux v5.6 and one
of them produces a new warning message from the kernel about busybox
(v1.31.1)
kernel: process '/bin/busybox' started with executable stack
Got similar discussion about klibc 2 monthes ago, look at
https://lists.zytor.com/archives/klibc/2020-February/004271.html
The target in question is a mips64 (octeon3). We have other targets
(mips32, armv7, ppc32, ppc64) which don't complain.
Some searching led me to
https://lore.kernel.org/lkml/20191208171918.GC19716@avx2/
Which suggests I should be filing a bug report with the vendor so here
I am.
Did you have a look into busybox bugzilla ? https://bugs.busybox.net/
Here's some readelf output from the binary
Can you perform "objdump -x " on your binary ?
I tried readelf on my busybox binary (ppc32), I get:
Elf file type is EXEC (Executable file)
Entry point 0x100046bc
There are 8 program headers, starting at offset 52
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
PHDR 0x000034 0x10000034 0x10000034 0x00100 0x00100 R E 0x4
INTERP 0x000134 0x10000134 0x10000134 0x0000d 0x0000d R 0x1
[Requesting program interpreter: /lib/ld.so.1]
LOAD 0x000000 0x10000000 0x10000000 0xbbb40 0xbbb40 R E 0x10000
LOAD 0x0bbb40 0x100cbb40 0x100cbb40 0x0029f 0x01c58 RWE 0x10000
DYNAMIC 0x0bbb90 0x100cbb90 0x100cbb90 0x000e8 0x000e8 RW 0x4
NOTE 0x000144 0x10000144 0x10000144 0x00020 0x00020 R 0x4
GNU_EH_FRAME 0x0bba18 0x100bba18 0x100bba18 0x00024 0x00024 R 0x4
GNU_STACK 0x000000 0x00000000 0x00000000 0x00000 0x00000 RW 0x10
As a comparison, for the klibc topic I was mentionning earlier, I get:
Elf file type is EXEC (Executable file)
Entry point 0x10000140
There are 5 program headers, starting at offset 52
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
PHDR 0x000034 0x10000034 0x10000034 0x000a0 0x000a0 R E 0x4
INTERP 0x0000d4 0x100000d4 0x100000d4 0x0002a 0x0002a R 0x1
[Requesting program interpreter:
/lib/klibc-WRQRzWcFMzsfxuuIUVGHxDcgmhA.so]
LOAD 0x000000 0x10000000 0x10000000 0x10928 0x10928 R E 0x10000
LOAD 0x010928 0x10020928 0x10020928 0x00144 0x04880 RW 0x10000
GNU_STACK 0x000000 0x00000000 0x00000000 0x00000 0x00000 RWE 0x10
Which here clearly shows the GNU_STACK is RWE in the problematic case.
In your readelfs, we can't see the stack.
Christophe
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