* [PATCH AUTOSEL 6.1 44/61] ELF: fix kernel.randomize_va_space double read
[not found] <20240801002803.3935985-1-sashal@kernel.org>
@ 2024-08-01 0:26 ` Sasha Levin
0 siblings, 0 replies; only message in thread
From: Sasha Levin @ 2024-08-01 0:26 UTC (permalink / raw)
To: linux-kernel, stable
Cc: Alexey Dobriyan, Kees Cook, Sasha Levin, viro, brauner,
linux-fsdevel, linux-mm
From: Alexey Dobriyan <adobriyan@gmail.com>
[ 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>
---
fs/binfmt_elf.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
index e6c9c0e084486..89e7e4826efce 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1009,7 +1009,8 @@ static int load_elf_binary(struct linux_binprm *bprm)
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);
@@ -1301,7 +1302,7 @@ static int load_elf_binary(struct linux_binprm *bprm)
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
--
2.43.0
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