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b=ZQOR8l4fPF3o6+d47sYqpOAWfinX9pej0uoD0jaVG3Y6G+RePxzLHaKObfSDZ1y/b TH3xJovIyBd4FDFBL7sYNeadPeII4uyxR56KVMuwduJwRfkD1DeSr2fC7sLMRzksvl pSPb3LH+wBmkmZQpecRvPWq3Vu57+pij0lydL2Ymvs7kbmWD5/BYOIxIvO60GLgpBq 40LxRvaKF5U7gvogjDuoiGgzKGSGepkTgS/G+gJnDyyXsqIKqzdt8PV0hwZOUybxPt z3XcrFNEU/C0ewcAtWeTpdkApHXchpQYqpZPkrPJJYBWPupFBVtAxM0YiLXLtF1JUV YWLlvGpgYavjA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Alexey Dobriyan , Kees Cook , Sasha Levin , viro@zeniv.linux.org.uk, brauner@kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH AUTOSEL 5.10 27/38] ELF: fix kernel.randomize_va_space double read Date: Wed, 31 Jul 2024 20:35:33 -0400 Message-ID: <20240801003643.3938534-27-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240801003643.3938534-1-sashal@kernel.org> References: <20240801003643.3938534-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 5.10.223 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: 9pzu6isijhi899b3ow1hnctdprs15w6h X-Rspamd-Queue-Id: 2B748A0008 X-Rspamd-Server: rspam11 X-HE-Tag: 1722472710-92715 X-HE-Meta: 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 WU4BBCUE 9sVpMsRhkxBZ0tLD2J5hF9s4ABngd3UKz1SKGisANEXdjmfzoxCA6FNJ+oRXT0HyWwOALU9tabG0ziv4ves/RQaQBswnYa1dH4BItx0mmv48kxg3gdd0qFSRF8+pYheq6CC5jUoUYI43cVo9NGiMhMtXQoJ9Hj+9EJqHankfR0gtbnuGw4meDrCkOhB+C3Lk3rJMjqneAzyFBYSxGnXcO7wc8B6Wag/vYOxiqPN+j4GUFvC5PF8LNEg1wqLE5vt/RYTRkFqiGbTiC2GzI3hGYDVbt3ZODE6DDhrvIFxrjv5liW88= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Alexey Dobriyan [ 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 Link: https://lore.kernel.org/r/3329905c-7eb8-400a-8f0a-d87cff979b5b@p183 Signed-off-by: Kees Cook Signed-off-by: Sasha Levin --- 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 ccc4c6d8a578f..dcca9fe747496 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1005,7 +1005,8 @@ 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); @@ -1275,7 +1276,7 @@ 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