Hi Ben,
On 10/7/19 7:29 PM, Ben Hutchings wrote:
On Tue, 2019-01-22 at 21:31 -0800, Richard Henderson wrote:
On 1/22/19 1:39 AM, Philippe Mathieu-Daudé wrote:
Hi Ben,
On 1/22/19 6:43 AM, Michael Tokarev wrote:
Forwarding to qemu-devel@
http://bugs.debian.org/919921
Thanks!
20.01.2019 20:55, Ben Hutchings wrote:
Package: qemu-user
Version: 1:3.1+dfsg-2
Severity: normal
Tags: patch
I've been building and testing klibc across many architectures using
qemu-user, and I found that qemu-user fails to load a few programs on
a few architectures, reporting an EINVAL error code. Here's the
"readelf -l" output for one such program:
Elf file type is EXEC (Executable file)
Entry point 0x10000100
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 0x4
INTERP 0x0000d4 0x100000d4 0x100000d4 0x0002a 0x0002a
R 0x1
[Requesting program interpreter:
/lib/klibc-R7FVdnsTBUFpWPgCV6FR07b-mf8.so]
LOAD 0x000000 0x10000000 0x10000000 0x002f8 0x002f8 R
E 0x10000
LOAD 0x010000 0x10020000 0x10020000 0x00000 0x08000
RW 0x10000
GNU_STACK 0x000000 0x00000000 0x00000000 0x00000 0x00000
RWE 0x10
Section to Segment mapping:
Segment Sections...
00
01 .interp
02 .interp .text .rodata .eh_frame
03 .bss
04
The unusual feature of this program, and all the others that failed,
is that there is a LOAD segment with a file-size of 0 (i.e. only BSS,
no initialised data). load_elf_image() will try to mmap() initialised
data for this section even though there is none and a length of 0 is
invalid.
The change that seems to fix this is to skip the mmap() in this case:
Is there a reason why my fix can't be applied? Do I need to open a bug
report in Launchpad for this?
Simply send your patch formally to qemu-de...@nongnu.org.
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -2316,11 +2316,13 @@ static void load_elf_image(const char *i
vaddr_ps = TARGET_ELF_PAGESTART(vaddr);
vaddr_len = TARGET_ELF_PAGELENGTH(eppnt->p_filesz +
vaddr_po);
- error = target_mmap(vaddr_ps, vaddr_len,
- elf_prot, MAP_PRIVATE | MAP_FIXED,
- image_fd, eppnt->p_offset - vaddr_po);
- if (error == -1) {
- goto exit_perror;
+ if (vaddr_len != 0) {
This is probably not the good fix, since now your process doesn't have
anything mapped to use his BSS :)
Not true. The mapping happens in zero_bss.
What about this fix instead, using the segment memory size rather than
the file size:
-- >8 --
@@ -2314,7 +2314,7 @@ static void load_elf_image(const char *image_name,
int image_fd,
vaddr = load_bias + eppnt->p_vaddr;
vaddr_po = TARGET_ELF_PAGEOFFSET(vaddr);
vaddr_ps = TARGET_ELF_PAGESTART(vaddr);
- vaddr_len = TARGET_ELF_PAGELENGTH(eppnt->p_filesz + vaddr_po);
+ vaddr_len = TARGET_ELF_PAGELENGTH(eppnt->p_memsz + vaddr_po);
error = target_mmap(vaddr_ps, vaddr_len,
elf_prot, MAP_PRIVATE | MAP_FIXED,
No, there's only filesz bytes in the file. I'd expect zero_bss to map over the
extra that you just mapped, but it doesn't help.
r~
