https://bugs.kde.org/show_bug.cgi?id=353192
Patrick Collins <pscoll...@google.com> changed:
What |Removed |Added
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CC| |pscoll...@google.com
--- Comment #4 from Patrick Collins <pscoll...@google.com> ---
I was bitten by this as well. I ended up with program headers that looked like
this:
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x00000000005eabf4 0x00000000005eabf4 R**W**E 200000
LOAD 0x0000000000600000 0x0000000000800000 0x0000000000800000
0x000000000003b3f0 0x000000000004efe8 RW 200000
DYNAMIC 0x000000000060f460 0x000000000080f460 0x000000000080f460
0x0000000000000180 0x0000000000000180 RW 8
NOTE 0x00000000000001c8 0x00000000000001c8 0x00000000000001c8
0x0000000000000024 0x0000000000000024 R 4
GNU_EH_FRAME 0x000000000057c050 0x000000000057c050 0x000000000057c050
0x000000000001600c 0x000000000001600c R 4
GNU_STACK 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000000000 0x0000000000000000 RW 10
GNU_RELRO 0x0000000000600000 0x0000000000800000 0x0000000000800000
0x0000000000011000 0x0000000000011000 R 1
where the W flag in section 00 was caused by a combination of unusual
__attribute__((__section__(foo))) annotations in GCC. I am also on Ubuntu, with
amd64. I think this is properly called a bug, at least on amd64, because there
is nothing in any standard that prevents .text sections from being mmaped with
rwx permissions.
As far as I can tell, moving amd64 to the same bucket as x86 and accepting r.x
permissions would be harmless, since Valgrind will only try to read in debug
symbols for a particular section if it finds *both* a section marked as
executable *and* a .debug entry that corresponds to that section. I assume the
rationale here is that if users are trying to treat a writeable section as a
text section, then they're probably doing something wrong --- but this won't
change existing behavior unless the user also provides debug info corresponding
to that section (in which case they probably really do want to treat that
section as text-like).
At the very least, emitting a warning when --trace-symbtab is turned on would
be helpful, because this was very difficult to track down.
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