From: Mark Wielaard Date: Tue, 19 May 2015 11:39:39 +0000 (+0200) Subject: libdwfl: Don't allocate all phdrs on the stack in elf_from_remote_memory. X-Git-Tag: elfutils-0.162~38 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9202fe132caea838cc7e2c7864e0ee702e62f155;p=thirdparty%2Felfutils.git libdwfl: Don't allocate all phdrs on the stack in elf_from_remote_memory. Signed-off-by: Mark Wielaard --- diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog index ef0397301..080825ed1 100644 --- a/libdwfl/ChangeLog +++ b/libdwfl/ChangeLog @@ -1,3 +1,8 @@ +2015-05-19 Mark Wielaard + + * 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 * linux-kernel-modules.c (dwfl_linux_kernel_find_elf): malloc and diff --git a/libdwfl/elf-from-memory.c b/libdwfl/elf-from-memory.c index b35fac719..ed8f6e920 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 @@ -63,11 +63,15 @@ 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; unsigned char *buffer = malloc (initial_bufsize); - if (buffer == NULL) + if (unlikely (buffer == NULL)) { no_memory: __libdwfl_seterrno (DWFL_E_NOMEM); @@ -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; + + phdrsp = malloc (sizeof (phdrsn)); + if (unlikely (phdrsp == NULL)) + { + free (buffer); + goto no_memory; + } + phdrsn *phdrs = (phdrsn *) phdrsp; - xlateto.d_buf = &phdrs; - xlateto.d_size = sizeof phdrs; + 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);