Memory safety (use-after-free) in kernel binder VMA handling (Android binder driver)

diff --git a/.get_maintainer.ignore b/.get_maintainer.ignore index e8d2269bad9d00..60b6b2a374cd6e 100644 --- a/.get_maintainer.ignore +++ b/.get_maintainer.ignore @@ -1,6 +1,7 @@ Alan Cox <alan@lxorguk.ukuu.org.uk> Alan Cox <root@hraefn.swansea.linux.org.uk> Alyssa Rosenzweig <alyssa@rosenzweig.io> +Askar Safin <safinaskar@gmail.com> Christoph Hellwig <hch@lst.de> Jeff Kirsher <jeffrey.t.kirsher@intel.com> Marc Gonzalez <marc.w.gonzalez@free.fr> diff --git a/Documentation/process/security-bugs.rst b/Documentation/process/security-bugs.rst index c0cf93e11565e2..27b028e8586104 100644 --- a/Documentation/process/security-bugs.rst +++ b/Documentation/process/security-bugs.rst @@ -5,8 +5,138 @@ Security bugs Linux kernel developers take security very seriously. As such, we'd like to know when a security bug is found so that it can be fixed and -disclosed as quickly as possible. Please report security bugs to the -Linux kernel security team. +disclosed as quickly as possible. + +Preparing your report +--------------------- + +Like with any bug report, a security bug report requires a lot of analysis work +from the developers, so the more information you can share about the issue, the +better. Please review the procedure outlined in +Documentation/admin-guide/reporting-issues.rst if you are unclear about what +information is helpful. The following information are absolutely necessary in +**any** security bug report: + + * **affected kernel version range**: with no version indication, your report + will not be processed. A significant part of reports are for bugs that + have already been fixed, so it is extremely important that vulnerabilities + are verified on recent versions (development tree or latest stable + version), at least by verifying that the code has not changed since the + version where it was detected. + + * **description of the problem**: a detailed description of the problem, with + traces showing its manifestation, and why you consider that the observed + behavior as a problem in the kernel, is necessary. + + * **reproducer**: developers will need to be able to reproduce the problem to + consider a fix as effective. This includes both a way to trigger the issue + and a way to confirm it happens. A reproducer with low complexity + dependencies will be needed (source code, shell script, sequence of + instructions, file-system image etc). Binary-only executables are not + accepted. Working exploits are extremely helpful and will not be released + without consent from the reporter, unless they are already public. By + definition if an issue cannot be reproduced, it is not exploitable, thus it + is not a security bug. + + * **conditions**: if the bug depends on certain configuration options, + sysctls, permissions, timing, code modifications etc, these should be + indicated. + +In addition, the following information are highly desirable: + + * **suspected location of the bug**: the file names and functions where the + bug is suspected to be present are very important, at least to help forward + the report to the appropriate maintainers. When not possible (for example, + "system freezes each time I run this command"), the security team will help + identify the source of the bug. + + * **a proposed fix**: bug reporters who have analyzed the cause of a bug in + the source code almost always have an accurate idea on how to fix it, + because they spent a long time studying it and its implications. Proposing + a tested fix will save maintainers a lot of time, even if the fix ends up + not being the right one, because it helps understand the bug. When + proposing a tested fix, please always format it in a way that can be + immediately merged (see Documentation/process/submitting-patches.rst). + This will save some back-and-forth exchanges if it is accepted, and you + will be credited for finding and fixing this issue. Note that in this case + only a ``Signed-off-by:`` tag is needed, without ``Reported-by:`` when the + reporter and author are the same. + + * **mitigations**: very often during a bug analysis, some ways of mitigating + the issue appear. It is useful to share them, as they can be helpful to + keep end users protected during the time it takes them to apply the fix. + +Identifying contacts +-------------------- + +The most effective way to report a security bug is to send it directly to the +affected subsystem's maintainers and Cc: the Linux kernel security team. Do +not send it to a public list at this stage, unless you have good reasons to +consider the issue as being public or trivial to discover (e.g. result of a +widely available automated vulnerability scanning tool that can be repeated by +anyone). + +If you're sending a report for issues affecting multiple parts in the kernel, +even if they're fairly similar issues, please send individual messages (think +that maintainers will not all work on the issues at the same time). The only +exception is when an issue concerns closely related parts maintained by the +exact same subset of maintainers, and these parts are expected to be fixed all +at once by the same commit, then it may be acceptable to report them at once. + +One difficulty for most first-time reporters is to figure the right list of +recipients to send a report to. In the Linux kernel, all official maintainers +are trusted, so the consequences of accidentally including the wrong maintainer +are essentially a bit more noise for that person, i.e. nothing dramatic. As +such, a suitable method to figure the list of maintainers (which kernel +security officers use) is to rely on the get_maintainer.pl script, tuned to +only report maintainers. This script, when passed a file name, will look for +its path in the MAINTAINERS file to figure a hierarchical list of relevant +maintainers. Calling it a first time with the finest level of filtering will +most of the time return a short list of this specific file's maintainers:: + + $ ./scripts/get_maintainer.pl --no-l --no-r --pattern-depth 1 \ + drivers/example.c + Developer One <dev1@example.com> (maintainer:example driver) + Developer Two <dev2@example.org> (maintainer:example driver) + +These two maintainers should then receive the message. If the command does not +return anything, it means the affected file is part of a wider subsystem, so we +should be less specific:: + + $ ./scripts/get_maintainer.pl --no-l --no-r drivers/example.c + Developer One <dev1@example.com> (maintainer:example subsystem) + Developer Two <dev2@example.org> (maintainer:example subsystem) + Developer Three <dev3@example.com> (maintainer:example subsystem [GENERAL]) + Developer Four <dev4@example.org> (maintainer:example subsystem [GENERAL]) + +Here, picking the first, most specific ones, is sufficient. When the list is +long, it is possible to produce a comma-delimited e-mail address list on a +single line suitable for use in the To: field of a mailer like this:: + + $ ./scripts/get_maintainer.pl --no-tree --no-l --no-r --no-n --m \ + --no-git-fallback --no-substatus --no-rolestats --no-multiline \ + --pattern-depth 1 drivers/example.c + dev1@example.com, dev2@example.org + +or this for the wider list:: + + $ ./scripts/get_maintainer.pl --no-tree --no-l --no-r --no-n --m \ + --no-git-fallback --no-substatus --no-rolestats --no-multiline \ + drivers/example.c + dev1@example.com, dev2@example.org, dev3@example.com, dev4@example.org + +If at this point you're still facing difficulties spotting the right +maintainers, **and only in this case**, it's possible to send your report to +the Linux kernel security team only. Your message will be triaged, and you +will receive instructions about whom to contact, if needed. Your message may +equally be forwarded as-is to the relevant maintainers. + +Sending the report +------------------ + +Reports are to be sent over e-mail exclusively. Please use a working e-mail +address, preferably the same that you want to appear in ``Reported-by`` tags +if any. If unsure, send your report to yourself first. The security team and maintainers almost always require additional information beyond what was initially provided in a report and rely on @@ -18,20 +148,12 @@ run additional tests. Reports where the reporter does not respond promptly or cannot effectively discuss their findings may be abandoned if the communication does not quickly improve. -As it is with any bug, the more information provided the easier it -will be to diagnose and fix. Please review the procedure outlined in -'Documentation/admin-guide/reporting-issues.rst' if you are unclear about what -information is helpful. Any exploit code is very helpful and will not -be released without consent from the reporter unless it has already been -made public. - +The report must be sent to maintainers, with the security team in ``Cc:``. The Linux kernel security team can be contacted by email at <security@kernel.org>. This is a private list of security officers -who will help verify the bug report and develop and release a fix. -If you already have a fix, please include it with your report, as -that can speed up the process considerably. It is possible that the -security team will bring in extra help from area maintainers to -understand and fix the security vulnerability. +who will help verify the bug report and assist developers working on a fix. +It is possible that the security team will bring in extra help from area +maintainers to understand and fix the security vulnerability. Please send **plain text** emails without attachments where possible. It is much harder to have a context-quoted discussion about a complex @@ -42,7 +164,9 @@ reproduction steps, and follow it with a proposed fix, all in plain text. Markdown, HTML and RST formatted reports are particularly frowned upon since they're quite hard to read for humans and encourage to use dedicated viewers, sometimes online, which by definition is not acceptable for a confidential -security report. +security report. Note that some mailers tend to mangle formatting of plain +text by default, please consult Documentation/process/email-clients.rst for +more info. Disclosure and embargoed information ------------------------------------ diff --git a/drivers/android/binder/page_range.rs b/drivers/android/binder/page_range.rs index 9dfc154e5dd4e8..b57e0c7ba3f1f8 100644 --- a/drivers/android/binder/page_range.rs +++ b/drivers/android/binder/page_range.rs @@ -13,6 +13,8 @@ // // The shrinker will use trylock methods because it locks them in a different order. +use crate::AssertSync; + use core::{ marker::PhantomPinned, mem::{size_of, size_of_val, MaybeUninit}, @@ -143,14 +145,14 @@ pub(crate) struct ShrinkablePageRange { } // We do not define any ops. For now, used only to check identity of vmas. -static BINDER_VM_OPS: bindings::vm_operations_struct = pin_init::zeroed(); +static BINDER_VM_OPS: AssertSync<bindings::vm_operations_struct> = AssertSync(pin_init::zeroed()); // To ensure that we do not accidentally install pages into or zap pages from the wrong vma, we // check its vm_ops and private data before using it. fn check_vma(vma: &virt::VmaRef, owner: *const ShrinkablePageRange) -> Option<&virt::VmaMixedMap> { // SAFETY: Just reading the vm_ops pointer of any active vma is safe. let vm_ops = unsafe { (*vma.as_ptr()).vm_ops }; - if !ptr::eq(vm_ops, &BINDER_VM_OPS) { + if !ptr::eq(vm_ops, &BINDER_VM_OPS.0) { return None; } @@ -342,7 +344,7 @@ impl ShrinkablePageRange { // SAFETY: We own the vma, and we don't use any methods on VmaNew that rely on // `vm_ops`. - unsafe { (*vma.as_ptr()).vm_ops = &BINDER_VM_OPS }; + unsafe { (*vma.as_ptr()).vm_ops = &BINDER_VM_OPS.0 }; Ok(num_pages) } diff --git a/drivers/android/binder/rust_binder_main.rs b/drivers/android/binder/rust_binder_main.rs index aa5f2a75adb47e..014010662df82e 100644 --- a/drivers/android/binder/rust_binder_main.rs +++ b/drivers/android/binder/rust_binder_main.rs @@ -306,7 +306,7 @@ impl kernel::Module for BinderModule { /// Makes the inner type Sync. #[repr(transparent)] pub struct AssertSync<T>(T); -// SAFETY: Used only to insert `file_operations` into a global, which is safe. +// SAFETY: Used only to insert C bindings types into globals, which is safe. unsafe impl<T> Sync for AssertSync<T> {} /// File operations that rust_binderfs.c can use. diff --git a/drivers/comedi/comedi_fops.c b/drivers/comedi/comedi_fops.c index 48a8a607a84c26..0df9f4636fb6bc 100644 --- a/drivers/comedi/comedi_fops.c +++ b/drivers/comedi/comedi_fops.c @@ -793,13 +793,15 @@ static void do_become_nonbusy(struct comedi_device *dev, __comedi_clear_subdevice_runflags(s, COMEDI_SRF_RUNNING | COMEDI_SRF_BUSY); spin_unlock_irqrestore(&s->spin_lock, flags); - if (comedi_is_runflags_busy(runflags)) { + if (async) { /* * "Run active" counter was set to 1 when setting up the * command. Decrement it and wait for it to become 0. */ - comedi_put_is_subdevice_running(s); - wait_for_completion(&async->run_complete); + if (comedi_is_runflags_busy(runflags)) { + comedi_put_is_subdevice_running(s); + wait_for_completion(&async->run_complete); + } comedi_buf_reset(s); async->inttrig = NULL; kfree(async->cmd.chanlist); diff --git a/drivers/comedi/drivers.c b/drivers/comedi/drivers.c index db225a3bf0128c..5ab96b5eefd135 100644 --- a/drivers/comedi/drivers.c +++ b/drivers/comedi/drivers.c @@ -1063,6 +1063,14 @@ int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it) ret = -EIO; goto out; } + if (IS_ENABLED(CONFIG_LOCKDEP)) { + /* + * dev->spinlock is for private use by the attached low-level + * driver. Reinitialize it to stop lock-dependency tracking + * between attachments to different low-level drivers. + */ + spin_lock_init(&dev->spinlock); + } dev->driver = driv; dev->board_name = dev->board_ptr ? *(const char **)dev->board_ptr : dev->driver->driver_name; diff --git a/drivers/comedi/drivers/dt2815.c b/drivers/comedi/drivers/dt2815.c index 03ba2fd18a2169..d066dc303520b9 100644 --- a/drivers/comedi/drivers/dt2815.c +++ b/drivers/comedi/drivers/dt2815.c @@ -175,6 +175,18 @@ static int dt2815_attach(struct comedi_device *dev, struct comedi_devconfig *it) ? current_range_type : voltage_range_type; } + /* + * Check if hardware is present before attempting any I/O operations. + * Reading 0xff from status register typically indicates no hardware + * on the bus (floating bus reads as all 1s). + */ + if (inb(dev->iobase + DT2815_STATUS) == 0xff) { + dev_err(dev->class_dev, + "No hardware detected at I/O base 0x%lx\n", + dev->iobase); + return -ENODEV; + } + /* Init the 2815 */ outb(0x00, dev->iobase + DT28 ... 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