MAP_FIXED_NOREPLACE appears to break older i386 binaries
From: Russell King - ARM Linux admin
Date: Sat Oct 05 2019 - 19:32:42 EST
Under a 4.19 kernel (debian stable), I am surprised to find that some
previously working i386 binaries no longer work, whereas others are
fine. ls, for example, dies with a SEGV, but bash is fine.
Looking at the kernel log reveals:
[13117.361000] 20899 (ls): Uhuuh, elf segment at 0000000008065000 requested but
the memory is mapped already
[13120.367221] 20935 (vdir): Uhuuh, elf segment at 0000000008065000 requested but the memory is mapped already
[13122.891253] 20936 (ls): Uhuuh, elf segment at 0000000008065000 requested but
the memory is mapped already
[13137.719143] 20940 (ls): Uhuuh, elf segment at 0000000008065000 requested but
the memory is mapped already
[13139.202469] 20978 (ls): Uhuuh, elf segment at 0000000008065000 requested but
the memory is mapped already
[13158.093533] 21007 (ls): Uhuuh, elf segment at 0000000008065000 requested but
the memory is mapped already
[13221.920939] 21021 (objdump): Uhuuh, elf segment at 00000000080a1000 requested but the memory is mapped already
Looking at /bin/ls:
Program Header:
PHDR off 0x00000034 vaddr 0x08048034 paddr 0x08048034 align 2**2
filesz 0x00000120 memsz 0x00000120 flags r-x
INTERP off 0x00000154 vaddr 0x08048154 paddr 0x08048154 align 2**0
filesz 0x00000013 memsz 0x00000013 flags r--
LOAD off 0x00000000 vaddr 0x08048000 paddr 0x08048000 align 2**12
filesz 0x0001d620 memsz 0x0001d620 flags r-x
LOAD off 0x0001d950 vaddr 0x08065950 paddr 0x08065950 align 2**12
filesz 0x00000a50 memsz 0x000016e4 flags rw-
DYNAMIC off 0x0001dec4 vaddr 0x08065ec4 paddr 0x08065ec4 align 2**2
filesz 0x00000100 memsz 0x00000100 flags rw-
NOTE off 0x00000168 vaddr 0x08048168 paddr 0x08048168 align 2**2
filesz 0x00000044 memsz 0x00000044 flags r--
EH_FRAME off 0x00018e68 vaddr 0x08060e68 paddr 0x08060e68 align 2**2
filesz 0x00000774 memsz 0x00000774 flags r--
STACK off 0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**4
filesz 0x00000000 memsz 0x00000000 flags rw-
RELRO off 0x0001d950 vaddr 0x08065950 paddr 0x08065950 align 2**0
filesz 0x000006b0 memsz 0x000006b0 flags r--
Note that the executable part of ls extends from 0x08048000 for
0x0001d620 bytes in memory and file, which takes that up to
0x08065620. The rw data section starts at 0x08065950.
Seems we've broken older i386 binaries with commit ad55eac74f20
("elf: enforce MAP_FIXED on overlaying elf segments"). Maybe the
MAP_FIXED_NOREPLACE stuff needs to have an on/off switch?
Here's the objdump -h output for the same binary:
Sections:
Idx Name Size VMA LMA File off Algn
0 .interp 00000013 08048154 08048154 00000154 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
1 .note.ABI-tag 00000020 08048168 08048168 00000168 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
2 .note.gnu.build-id 00000024 08048188 08048188 00000188 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
3 .gnu.hash 0000003c 080481ac 080481ac 000001ac 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
4 .dynsym 00000840 080481e8 080481e8 000001e8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
5 .gnu.liblist 000000c8 08048a28 08048a28 00000a28 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
6 .gnu.version 00000108 08049020 08049020 00001020 2**1
CONTENTS, ALLOC, LOAD, READONLY, DATA
7 .gnu.version_r 000000c0 08049128 08049128 00001128 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
8 .rel.dyn 00000048 080491e8 080491e8 000011e8 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
9 .rel.plt 00000390 08049230 08049230 00001230 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
10 .init 00000023 080495c0 080495c0 000015c0 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
11 .plt 00000730 080495f0 080495f0 000015f0 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
12 .text 00013274 08049d20 08049d20 00001d20 2**4
CONTENTS, ALLOC, LOAD, READONLY, CODE
13 .fini 00000014 0805cf94 0805cf94 00014f94 2**2
CONTENTS, ALLOC, LOAD, READONLY, CODE
14 .rodata 00003ea8 0805cfc0 0805cfc0 00014fc0 2**5
CONTENTS, ALLOC, LOAD, READONLY, DATA
15 .eh_frame_hdr 00000774 08060e68 08060e68 00018e68 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
16 .eh_frame 0000341c 080615dc 080615dc 000195dc 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
17 .dynstr 0000064c 080649f8 080649f8 0001c9f8 2**0
CONTENTS, ALLOC, LOAD, READONLY, DATA
18 .gnu.conflict 000005dc 08065044 08065044 0001d044 2**2
CONTENTS, ALLOC, LOAD, READONLY, DATA
19 .init_array 00000004 08065950 08065950 0001d950 2**2
CONTENTS, ALLOC, LOAD, DATA
20 .fini_array 00000004 08065954 08065954 0001d954 2**2
CONTENTS, ALLOC, LOAD, DATA
21 .jcr 00000004 08065958 08065958 0001d958 2**2
CONTENTS, ALLOC, LOAD, DATA
22 .data.rel.ro 00000544 08065980 08065980 0001d980 2**6
CONTENTS, ALLOC, LOAD, DATA
23 .dynamic 00000100 08065ec4 08065ec4 0001dec4 2**2
CONTENTS, ALLOC, LOAD, DATA
24 .got 00000024 08065fc4 08065fc4 0001dfc4 2**2
CONTENTS, ALLOC, LOAD, DATA
25 .got.plt 000001d4 08066000 08066000 0001e000 2**2
CONTENTS, ALLOC, LOAD, DATA
26 .data 000001a0 08066200 08066200 0001e200 2**6
CONTENTS, ALLOC, LOAD, DATA
27 .bss 00000c74 080663c0 080663c0 0001e3a0 2**6
ALLOC
28 .gnu_debuglink 00000010 00000000 00000000 0001e3a0 2**2
CONTENTS, READONLY
29 .gnu_debugdata 00001170 00000000 00000000 0001e3b0 2**0
CONTENTS, READONLY
30 .gnu.prelink_undo 000005dc 00000000 00000000 0001f520 2**2
CONTENTS, READONLY
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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