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Fri, 5 Aug 2022 14:01:52 GMT (envelope-from git) Date: Fri, 5 Aug 2022 14:01:52 GMT Message-Id: <202208051401.275E1qJv025590@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org From: Ed Maste Subject: git: f0687f3e0e4d - main - Clarify code comments on ASLR default settings List-Id: Commit messages for the main branch of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-main List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-dev-commits-src-main@freebsd.org X-BeenThere: dev-commits-src-main@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: emaste X-Git-Repository: src X-Git-Refname: refs/heads/main X-Git-Reftype: branch X-Git-Commit: f0687f3e0e4d09edce906308f79b312abd574553 Auto-Submitted: auto-generated ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1659708112; 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mx1.freebsd.org; none X-ThisMailContainsUnwantedMimeParts: N The branch main has been updated by emaste: URL: https://cgit.FreeBSD.org/src/commit/?id=f0687f3e0e4d09edce906308f79b312abd574553 commit f0687f3e0e4d09edce906308f79b312abd574553 Author: Ed Maste AuthorDate: 2022-08-05 14:01:07 +0000 Commit: Ed Maste CommitDate: 2022-08-05 14:01:16 +0000 Clarify code comments on ASLR default settings Sponsored by: The FreeBSD Foundation --- sys/kern/imgact_elf.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/sys/kern/imgact_elf.c b/sys/kern/imgact_elf.c index ca1a7aaca331..ca4c59089775 100644 --- a/sys/kern/imgact_elf.c +++ b/sys/kern/imgact_elf.c @@ -173,10 +173,9 @@ SYSCTL_NODE(__CONCAT(_kern_elf, __ELF_WORD_SIZE), OID_AUTO, aslr, #define ASLR_NODE_OID __CONCAT(__CONCAT(_kern_elf, __ELF_WORD_SIZE), _aslr) /* - * While for 64-bit machines ASLR works properly, there are - * still some problems when using 32-bit architectures. For this - * reason ASLR is only enabled by default when running native - * 64-bit non-PIE executables. + * Enable ASLR by default for 64-bit non-PIE binaries. 32-bit architectures + * have limited address space (which can cause issues for applications with + * high memory use) so we leave it off there. */ static int __elfN(aslr_enabled) = __ELF_WORD_SIZE == 64; SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, enable, CTLFLAG_RWTUN, @@ -185,7 +184,7 @@ SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, enable, CTLFLAG_RWTUN, ": enable address map randomization"); /* - * Enable ASLR only for 64-bit PIE binaries by default. + * Enable ASLR by default for 64-bit PIE binaries. */ static int __elfN(pie_aslr_enabled) = __ELF_WORD_SIZE == 64; SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, pie_enable, CTLFLAG_RWTUN, @@ -194,9 +193,9 @@ SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, pie_enable, CTLFLAG_RWTUN, ": enable address map randomization for PIE binaries"); /* - * Sbrk is now deprecated and it can be assumed, that in most - * cases it will not be used anyway. This setting is valid only - * for the ASLR enabled and allows for utilizing the bss grow region. + * Sbrk is deprecated and it can be assumed that in most cases it will not be + * used anyway. This setting is valid only with ASLR enabled, and allows ASLR + * to use the bss grow region. */ static int __elfN(aslr_honor_sbrk) = 0; SYSCTL_INT(ASLR_NODE_OID, OID_AUTO, honor_sbrk, CTLFLAG_RW,