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Fix prelink bug with small data on PowerPC
- From: "Joseph S. Myers" <joseph at codesourcery dot com>
- To: prelink at sourceware dot org
- Date: Thu, 15 Jan 2009 20:35:07 +0000 (UTC)
- Subject: Fix prelink bug with small data on PowerPC
This patch fixes a prelinker bug that appears on PowerPC with small
data.
I do not have a reduced testcase for this bug, only a large
filesystem. The failure involves uninitialized memory reads so
reducing tests is likely to be difficult.
A binary that exemplifies the problem has exactly two copy
relocations:
10017bec R_PPC_COPY stderr
10017bf0 R_PPC_COPY optarg
which relate to words in successive sections:
23 .sbss 00000004 10017bec 10017bec 00007bec 2**2
ALLOC
24 .bss 00000130 10017bf0 10017bf0 00007bec 2**3
ALLOC
The logic for handling multiple BSS sections looks for the first copy
relocation, in a sorted list, that is outside the first section.
Because this logic uses > instead of >=, it fails to detect a
relocation pointing immediately after the end of the first section.
In this case, there are no copy relocations pointing later in the
second section, so the loop ends with i == 2 rather than with a break
and then the code starts looking at the uninitialized
cr.rela[i].r_offset value. The fix simply makes the code use >=.
Please commit if OK.
2009-01-15 Joseph Myers <joseph@codesourcery.com>
* src/conflict.c (prelink_build_conflicts): Use >= not > to
determine whether a relocation points outside the first bss
section.
Index: src/conflict.c
===================================================================
--- src/conflict.c (revision 164)
+++ src/conflict.c (working copy)
@@ -651,7 +651,7 @@
{
for (i = 1; i < cr.count; ++i)
if (cr.rela[i].r_offset
- > dso->shdr[bss1].sh_addr + dso->shdr[bss1].sh_size)
+ >= dso->shdr[bss1].sh_addr + dso->shdr[bss1].sh_size)
break;
if (cr.rela[i].r_offset < dso->shdr[bss2].sh_addr)
{
--
Joseph S. Myers
joseph@codesourcery.com