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commit 62058ce612ed3459501b4c4332e268edfe977f59
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Author: Carlos O'Donell <carlos@redhat.com>
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Date: Mon Sep 29 13:14:21 2014 -0400
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Correctly size profiling reloc table (bug 17411)
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During auditing or profiling modes the dynamic loader
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builds a cache of the relocated PLT entries in order
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to reuse them when called again through the same PLT
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entry. This way the PLT entry is never completed and
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the call into the resolver always results in profiling
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or auditing code running.
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The problem is that the PLT relocation cache size
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is not computed correctly. The size of the cache
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should be "Size of a relocation result structure"
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x "Number of PLT-related relocations". Instead the
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code erroneously computes "Size of a relocation
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result" x "Number of bytes worth of PLT-related
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relocations". I can only assume this was a mistake
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in the understanding of the value of DT_PLTRELSZ
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which is the number of bytes of PLT-related relocs.
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We do have a DT_RELACOUNT entry, which is a count
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for dynamic relative relocs, but we have no
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DT_PLTRELCOUNT and thus we need to compute it.
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This patch corrects the computation of the size of the
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relocation table used by the glibc profiling code.
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For more details see:
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https://sourceware.org/ml/libc-alpha/2014-09/msg00513.html
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[BZ #17411]
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* elf/dl-reloc.c (_dl_relocate_object): Allocate correct amount for
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l_reloc_result.
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diff --git glibc-2.17-c758a686/elf/dl-reloc.c glibc-2.17-c758a686/elf/dl-reloc.c
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index d2c6dac..97a7119 100644
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--- glibc-2.17-c758a686/elf/dl-reloc.c
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+++ glibc-2.17-c758a686/elf/dl-reloc.c
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@@ -279,8 +279,12 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
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l->l_name);
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}
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- l->l_reloc_result = calloc (sizeof (l->l_reloc_result[0]),
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- l->l_info[DT_PLTRELSZ]->d_un.d_val);
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+ size_t sizeofrel = l->l_info[DT_PLTREL]->d_un.d_val == DT_RELA
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+ ? sizeof (ElfW(Rela))
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+ : sizeof (ElfW(Rel));
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+ size_t relcount = l->l_info[DT_PLTRELSZ]->d_un.d_val / sizeofrel;
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+ l->l_reloc_result = calloc (sizeof (l->l_reloc_result[0]), relcount);
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+
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if (l->l_reloc_result == NULL)
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{
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errstring = N_("\
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