linux-kernel - [PATCH] fs/binfmt_elf: fix PT_LOAD p

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Date:   Wed,  2 Feb 2022 14:14:33 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        "H.J. Lu" <hjl.tools@...il.com>, Kees Cook <keescook@...omium.org>,
        Mike Rapoport <rppt@...nel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        Rui Salvaterra <rsalvaterra@...il.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] fs/binfmt_elf: fix PT_LOAD p_align values for loaders

From: Mike Rapoport <rppt@...ux.ibm.com>

Rui Salvaterra reported that Aisleroit solitaire crashes with "Wrong
__data_start/_end pair" assertion from libgc after update to v5.17-rc1.

Bisection pointed to commit 9630f0d60fec ("fs/binfmt_elf: use PT_LOAD
p_align values for static PIE") that fixed handling of static PIEs, but
made the condition that guards load_bias calculation to exclude loader
binaries.

Restoring the check for presence of interpreter fixes the problem.

Fixes: 9630f0d60fec ("fs/binfmt_elf: use PT_LOAD p_align values for static PIE")
Reported-by: Rui Salvaterra <rsalvaterra@...il.com>
Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
---
 fs/binfmt_elf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index 605017eb9349..9e11e6f13e83 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1117,7 +1117,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
 			 * without MAP_FIXED nor MAP_FIXED_NOREPLACE).
 			 */
 			alignment = maximum_alignment(elf_phdata, elf_ex->e_phnum);
-			if (alignment > ELF_MIN_ALIGN) {
+			if (interpreter || alignment > ELF_MIN_ALIGN) {
 				load_bias = ELF_ET_DYN_BASE;
 				if (current->flags & PF_RANDOMIZE)
 					load_bias += arch_mmap_rnd();
-- 
2.34.1