http://sourceware.org/bugzilla/show_bug.cgi?id=16199
Bug ID: 16199
Summary: Objcopy crash when section alignment is zero
Product: binutils
Version: 2.25 (HEAD)
Status: NEW
Severity: normal
Priority: P2
Component: binutils
Assignee: unassigned at sourceware dot org
Reporter: goldstei at ugcs dot caltech.edu
Created attachment 7287
--> http://sourceware.org/bugzilla/attachment.cgi?id=7287&action=edit
Patch to avoid division by zero
When making a copy of an ARM 32 bit elf file generated by IAR. I found that
when copying a section we can get to a situation where, in the function
assign_file_posistion_for_load_sections() the p_align_valid flag is 1 when the
p_align flag is set to 0. This will cause a divide by zero error in
vma_page_aligned_bias().
I'm not sure if the p_align_valid flag should be set when the alignment is 0;
however I did make a patch that fixes the crash, by simply not calling
vma_page_aligned_bias().
Here is readelf's dump of the section headers that caused the crash,
specifically Fill1:
---
Section Headers:
[Nr] Name
Type Addr Off Size ES Lk Inf Al
Flags
... useless lines ...
[25] Fill1
PROGBITS 000060d8 554668 000028 01 0 0 0
[00000006]: ALLOC, EXEC
[26] Fill2
PROGBITS 00089240 554690 016db8 01 0 0 0
[00000006]: ALLOC, EXEC
---
These sections are filled with 0xffffffff. The ARM ELF spec does state that the
alignment of executable sections must be at least 32-bits. These contain no
code, so in that sense, the output may be in violation of the ELF spec. Still,
I think it makes sense for objcopy to behave defensively in this case.
I've attached a patch. If needs be, I can also generate a file that displays
the behavior.
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