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ELF: fix kernel.randomize_va_space double read 

[ Upstream commit 2a97388a807b6ab5538aa8f8537b2463c6988bd2 ]

ELF loader uses "randomize_va_space" twice. It is sysctl and can change
at any moment, so 2 loads could see 2 different values in theory with
unpredictable consequences.

Issue exactly one load for consistent value across one exec.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Link: https://lore.kernel.org/r/3329905c-7eb8-400a-8f0a-d87cff979b5b@p183
Signed-off-by: Kees Cook <kees@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Alexey Dobriyan 2024-06-21 21:54:50 +03:00 committed by Greg Kroah-Hartman
parent 3c9e7909df
commit 53f17409ab
1 changed files with 3 additions and 2 deletions
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5
fs/binfmt_elf.c
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@ -1008,7 +1008,8 @@ out_free_interp:
if (elf_read_implies_exec(*elf_ex, executable_stack))
current->personality |= READ_IMPLIES_EXEC;
if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
const int snapshot_randomize_va_space = READ_ONCE(randomize_va_space);
if (!(current->personality & ADDR_NO_RANDOMIZE) && snapshot_randomize_va_space)
current->flags |= PF_RANDOMIZE;
setup_new_exec(bprm);
@ -1300,7 +1301,7 @@ out_free_interp:
mm->end_data = end_data;
mm->start_stack = bprm->p;
if ((current->flags & PF_RANDOMIZE) && (randomize_va_space > 1)) {
if ((current->flags & PF_RANDOMIZE) && (snapshot_randomize_va_space > 1)) {
/*
* For architectures with ELF randomization, when executing
* a loader directly (i.e. no interpreter listed in ELF