Patch patchelf to fix misaligned load segments

This commit is contained in:
Emery Hemingway 2021-03-11 16:20:12 +01:00
parent 4c0a6e94f4
commit 7078c64a1c
3 changed files with 71 additions and 8 deletions

View File

@ -86,7 +86,8 @@ in nullPkgs // {
erisPatchHook = final.callPackage ./eris-patch-hook {
patchelf = prev.patchelf.overrideAttrs (attrs: {
patches = attrs.patched or [ ] ++ [ ./patchelf/dynstr.patch ];
patches = attrs.patched or [ ]
++ [ ./patchelf/dynstr.patch ./patchelf/shiftFile.patch ];
});
};

View File

@ -1,17 +1,19 @@
From c66ec32bbdb88b0b4be0203c539bc6e91b471554 Mon Sep 17 00:00:00 2001
From da00bd779e6f725eac6a01c0d3af6c1ba9543eda Mon Sep 17 00:00:00 2001
From: Emery Hemingway <ehmry@posteo.net>
Date: Fri, 19 Feb 2021 14:52:25 +0100
Subject: [PATCH] Expand LOAD segment to cover new .dynstr and .dynsym sections
This is not a robust fix, the first PT_LOAD segment is expanded
forward to cover .dynstr or .dynsym.
---
src/patchelf.cc | 40 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 40 insertions(+)
src/patchelf.cc | 44 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 44 insertions(+)
diff --git a/src/patchelf.cc b/src/patchelf.cc
index 50eb13a..f13f460 100644
index 50eb13a..1d5ecf3 100644
--- a/src/patchelf.cc
+++ b/src/patchelf.cc
@@ -760,6 +760,46 @@ void ElfFile<ElfFileParamNames>::writeReplacedSections(Elf_Off & curOff,
@@ -760,6 +760,50 @@ void ElfFile<ElfFileParamNames>::writeReplacedSections(Elf_Off & curOff,
curOff += roundUp(i.second.size(), sectionAlignment);
}
@ -39,8 +41,12 @@ index 50eb13a..f13f460 100644
+ debug("'%s' was moved out of a load segment…\n", sectionName.c_str());
+ for (auto & phdr : phdrs) {
+ if (rdi(phdr.p_type) == PT_LOAD) {
+ if (rdi(shdr.sh_offset) < rdi(phdr.p_offset)) {
+ Elf64_Xword gap = rdi(phdr.p_offset) - rdi(shdr.sh_offset);
+ auto sh_offset = rdi(shdr.sh_offset);
+ auto p_offset = rdi(phdr.p_offset);
+ if (sh_offset < p_offset) {
+ Elf64_Xword gap
+ = (p_offset - sh_offset)
+ + ((getPageSize()-1) & sh_offset);
+ debug("grow PT_LOAD segment by 0x%x to cover '%s'\n",
+ gap, sectionName.c_str());
+ wri(phdr.p_filesz, rdi(phdr.p_filesz) + gap);

View File

@ -0,0 +1,56 @@
From 167aba8e9cc5b7850df59731fc02de08608fc6a6 Mon Sep 17 00:00:00 2001
From: Emery Hemingway <ehmry@posteo.net>
Date: Thu, 11 Mar 2021 15:23:34 +0100
Subject: [PATCH] Set exact size of new load segment in executables
This fixes a bug where the length of new load segments did not
account for the offset of the segment within the load region.
---
src/patchelf.cc | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)
diff --git a/src/patchelf.cc b/src/patchelf.cc
index 287fea8..0c672e1 100644
--- a/src/patchelf.cc
+++ b/src/patchelf.cc
@@ -581,18 +581,6 @@ void ElfFile<ElfFileParamNames>::shiftFile(unsigned int extraPages, Elf_Addr sta
wri(phdrs[i].p_align, getPageSize());
}
}
-
- /* Add a segment that maps the new program/section headers and
- PT_INTERP segment into memory. Otherwise glibc will choke. */
- phdrs.resize(rdi(hdr->e_phnum) + 1);
- wri(hdr->e_phnum, rdi(hdr->e_phnum) + 1);
- Elf_Phdr & phdr = phdrs[rdi(hdr->e_phnum) - 1];
- wri(phdr.p_type, PT_LOAD);
- wri(phdr.p_offset, 0);
- wri(phdr.p_vaddr, wri(phdr.p_paddr, startPage));
- wri(phdr.p_filesz, wri(phdr.p_memsz, shift));
- wri(phdr.p_flags, PF_R | PF_W);
- wri(phdr.p_align, getPageSize());
}
@@ -957,6 +945,18 @@ void ElfFile<ElfFileParamNames>::rewriteSectionsExecutable()
startOffset += neededPages * getPageSize();
shiftFile(neededPages, firstPage);
+
+ /* Add a segment that maps the new program/section headers and
+ PT_INTERP segment into memory. Otherwise glibc will choke. */
+ phdrs.resize(rdi(hdr->e_phnum) + 1);
+ wri(hdr->e_phnum, rdi(hdr->e_phnum) + 1);
+ Elf_Phdr & phdr = phdrs[rdi(hdr->e_phnum) - 1];
+ wri(phdr.p_type, PT_LOAD);
+ wri(phdr.p_offset, 0);
+ wri(phdr.p_vaddr, wri(phdr.p_paddr, firstPage));
+ wri(phdr.p_filesz, wri(phdr.p_memsz, neededSpace));
+ wri(phdr.p_flags, PF_R | PF_W); // Can this be read-only?
+ wri(phdr.p_align, getPageSize());
}
--
2.29.2