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[PATCH 11/17] libdwfl: Don't allocate all phdrs on the stack in elf_from_remote_memory.
- From: Mark Wielaard <mjw at redhat dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Sat, 23 May 2015 23:10:24 +0200
- Subject: [PATCH 11/17] libdwfl: Don't allocate all phdrs on the stack in elf_from_remote_memory.
Signed-off-by: Mark Wielaard <mjw@redhat.com>
---
libdwfl/ChangeLog | 5 +++++
libdwfl/elf-from-memory.c | 57 ++++++++++++++++++++++++++++++++---------------
2 files changed, 44 insertions(+), 18 deletions(-)
diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index ef03973..080825e 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,5 +1,10 @@
2015-05-19 Mark Wielaard <mjw@redhat.com>
+ * elf-from-memory.c (elf_from_remote_memory): Don't allocate all
+ phdrs on the stack. Allocate with malloc and free when done.
+
+2015-05-19 Mark Wielaard <mjw@redhat.com>
+
* linux-kernel-modules.c (dwfl_linux_kernel_find_elf): malloc and
free alternate_name.
diff --git a/libdwfl/elf-from-memory.c b/libdwfl/elf-from-memory.c
index b35fac7..5595d96 100644
--- a/libdwfl/elf-from-memory.c
+++ b/libdwfl/elf-from-memory.c
@@ -1,5 +1,5 @@
/* Reconstruct an ELF file by reading the segments out of remote memory.
- Copyright (C) 2005-2011, 2014 Red Hat, Inc.
+ Copyright (C) 2005-2011, 2014, 2015 Red Hat, Inc.
This file is part of elfutils.
This file is free software; you can redistribute it and/or modify
@@ -63,6 +63,10 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
size_t maxread),
void *arg)
{
+ /* We might have to reserve some memory for the phdrs. Set to NULL
+ here so we can always safely free it. */
+ void *phdrsp = NULL;
+
/* First read in the file header and check its sanity. */
const size_t initial_bufsize = 256;
@@ -80,6 +84,7 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
{
read_error:
free (buffer);
+ free (phdrsp);
__libdwfl_seterrno (nread < 0 ? DWFL_E_ERRNO : DWFL_E_TRUNCATED);
return NULL;
}
@@ -88,6 +93,7 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
{
bad_elf:
free (buffer);
+ free (phdrsp);
__libdwfl_seterrno (DWFL_E_BADELF);
return NULL;
}
@@ -172,6 +178,7 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
if (newbuf == NULL)
{
free (buffer);
+ free (phdrsp);
goto no_memory;
}
buffer = newbuf;
@@ -184,14 +191,22 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
xlatefrom.d_buf = buffer;
}
- union
+ typedef union
{
Elf32_Phdr p32[phnum];
Elf64_Phdr p64[phnum];
- } phdrs;
+ } phdrsn;
- xlateto.d_buf = &phdrs;
- xlateto.d_size = sizeof phdrs;
+ phdrsp = malloc (sizeof (phdrsn));
+ if (phdrsp == NULL)
+ {
+ free (buffer);
+ goto no_memory;
+ }
+ phdrsn *phdrs = (phdrsn *) phdrsp;
+
+ xlateto.d_buf = phdrs;
+ xlateto.d_size = sizeof (phdrsn);
/* Scan for PT_LOAD segments to find the total size of the file image. */
size_t contents_size = 0;
@@ -234,9 +249,9 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
ehdr.e32.e_ident[EI_DATA]) == NULL)
goto libelf_error;
for (uint_fast16_t i = 0; i < phnum; ++i)
- if (phdrs.p32[i].p_type == PT_LOAD)
- if (handle_segment (phdrs.p32[i].p_vaddr, phdrs.p32[i].p_offset,
- phdrs.p32[i].p_filesz, phdrs.p32[i].p_memsz))
+ if (phdrs->p32[i].p_type == PT_LOAD)
+ if (handle_segment (phdrs->p32[i].p_vaddr, phdrs->p32[i].p_offset,
+ phdrs->p32[i].p_filesz, phdrs->p32[i].p_memsz))
goto bad_elf;
break;
@@ -245,9 +260,9 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
ehdr.e64.e_ident[EI_DATA]) == NULL)
goto libelf_error;
for (uint_fast16_t i = 0; i < phnum; ++i)
- if (phdrs.p64[i].p_type == PT_LOAD)
- if (handle_segment (phdrs.p64[i].p_vaddr, phdrs.p64[i].p_offset,
- phdrs.p64[i].p_filesz, phdrs.p64[i].p_memsz))
+ if (phdrs->p64[i].p_type == PT_LOAD)
+ if (handle_segment (phdrs->p64[i].p_vaddr, phdrs->p64[i].p_offset,
+ phdrs->p64[i].p_filesz, phdrs->p64[i].p_memsz))
goto bad_elf;
break;
@@ -276,7 +291,10 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
/* Now we know the size of the whole image we want read in. */
buffer = calloc (1, contents_size);
if (buffer == NULL)
- goto no_memory;
+ {
+ free (phdrsp);
+ goto no_memory;
+ }
switch (ehdr.e32.e_ident[EI_CLASS])
{
@@ -297,9 +315,9 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
case ELFCLASS32:
for (uint_fast16_t i = 0; i < phnum; ++i)
- if (phdrs.p32[i].p_type == PT_LOAD)
- if (handle_segment (phdrs.p32[i].p_vaddr, phdrs.p32[i].p_offset,
- phdrs.p32[i].p_filesz))
+ if (phdrs->p32[i].p_type == PT_LOAD)
+ if (handle_segment (phdrs->p32[i].p_vaddr, phdrs->p32[i].p_offset,
+ phdrs->p32[i].p_filesz))
goto read_error;
/* If the segments visible in memory didn't include the section
@@ -324,9 +342,9 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
case ELFCLASS64:
for (uint_fast16_t i = 0; i < phnum; ++i)
- if (phdrs.p64[i].p_type == PT_LOAD)
- if (handle_segment (phdrs.p64[i].p_vaddr, phdrs.p64[i].p_offset,
- phdrs.p64[i].p_filesz))
+ if (phdrs->p64[i].p_type == PT_LOAD)
+ if (handle_segment (phdrs->p64[i].p_vaddr, phdrs->p64[i].p_offset,
+ phdrs->p64[i].p_filesz))
goto read_error;
/* If the segments visible in memory didn't include the section
@@ -354,6 +372,9 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
break;
}
+ free (phdrsp);
+ phdrs = phdrsp = NULL;
+
/* Now we have the image. Open libelf on it. */
Elf *elf = elf_memory ((char *) buffer, contents_size);
--
1.8.3.1