[PATCH AUTOSEL 6.6 61/83] ELF: fix kernel.randomize_va_space double read

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Alexey Dobriyan <adobriyan@xxxxxxxxx>

[ 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@xxxxxxxxx>
Link: https://lore.kernel.org/r/3329905c-7eb8-400a-8f0a-d87cff979b5b@p183
Signed-off-by: Kees Cook <kees@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 7b3d2d4914073..fb2c8d14327ae 100644
--- a/fs/binfmt_elf.c
+++ b/fs/binfmt_elf.c
@@ -1008,7 +1008,8 @@ 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);
@@ -1300,7 +1301,7 @@ 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





[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [NTFS 3]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [NTFS 3]     [Samba]     [Device Mapper]     [CEPH Development]

  Powered by Linux