kernel.git/arch/um/os-Linux, branch linux-6.4.y

Revert "[PATCH] uml: export symbols added by GCC hardened"

2023-08-23T15:32:29Z

[ Upstream commit 8635e8df477bc77837886da206f4915576f88fec ] This reverts commit cead61a6717a9873426b08d73a34a325e3546f5d. It exported __stack_smash_handler and __guard, while they may not be defined by anyone. The code *declares* __stack_smash_handler and __guard. It does not create weak symbols. If no external library is linked, they are left undefined, but yet exported. If a loadable module tries to access non-existing symbols, bad things (a page fault, NULL pointer dereference, etc.) will happen. So, the current code is wrong and dangerous. If the code were written as follows, it would *define* them as weak symbols so modules would be able to get access to them. void (*__stack_smash_handler)(void *) __attribute__((weak)); EXPORT_SYMBOL(__stack_smash_handler); long __guard __attribute__((weak)); EXPORT_SYMBOL(__guard); In fact, modpost forbids exporting undefined symbols. It shows an error message if it detects such a mistake. ERROR: modpost: "..." [...] was exported without definition Unfortunately, it is checked only when the code is built as modular. The problem described above has been unnoticed for a long time because arch/um/os-Linux/user_syms.c is always built-in. With a planned change in Kbuild, exporting undefined symbols will always result in a build error instead of a run-time error. It is a good thing, but we need to fix the breakage in advance. One fix is to define weak symbols as shown above. An alternative is to export them conditionally as follows: #ifdef CONFIG_STACKPROTECTOR extern void __stack_smash_handler(void *); EXPORT_SYMBOL(__stack_smash_handler); external long __guard; EXPORT_SYMBOL(__guard); #endif This is what other architectures do; EXPORT_SYMBOL(__stack_chk_guard) is guarded by #ifdef CONFIG_STACKPROTECTOR. However, adding the #ifdef guard is not sensible because UML cannot enable the stack-protector in the first place! (Please note UML does not select HAVE_STACKPROTECTOR in Kconfig.) So, the code is already broken (and unused) in multiple ways. Just remove. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers Signed-off-by: Sasha Levin

Revert "um: Use swap() to make code cleaner"

2023-08-03T08:26:11Z

commit dddfa05eb58076ad60f9a66e7155a5b3502b2dd5 upstream. This reverts commit 9b0da3f22307af693be80f5d3a89dc4c7f360a85. The sigio.c is clearly user space code which is handled by arch/um/scripts/Makefile.rules (see USER_OBJS rule). The above mentioned commit simply broke this agreement, we may not use Linux kernel internal headers in them without thorough thinking. Hence, revert the wrong commit. Link: https://lkml.kernel.org/r/20230724143131.30090-1-andriy.shevchenko@linux.intel.com Signed-off-by: Andy Shevchenko Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202307212304.cH79zJp1-lkp@intel.com/ Cc: Anton Ivanov Cc: Herve Codina Cc: Jason A. Donenfeld Cc: Johannes Berg Cc: Rasmus Villemoes Cc: Richard Weinberger Cc: Yang Guang Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

Merge tag 'uml-for-linus-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

2023-05-04T02:02:03Z

Pull uml updates from Richard Weinberger: - Make stub data pages configurable - Make it harder to mix user and kernel code by accident * tag 'uml-for-linus-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: um: make stub data pages size tweakable um: prevent user code in modules um: further clean up user_syms um: don't export printf() um: hostfs: define our own API boundary um: add __weak for exported functions

um: make stub data pages size tweakable

2023-04-20T21:08:43Z

There's a lot of code here that hard-codes that the data is a single page, and right now that seems to be sufficient, but to make it easier to change this in the future, add a new STUB_DATA_PAGES constant and use it throughout the code. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: further clean up user_syms

2023-04-20T21:05:52Z

Make some cleanups, add and fix some comments and document here that we shouldn't export (libc) symbols for "_user.c" code, rather such should work like hostfs does now. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: don't export printf()

2023-04-20T21:05:35Z

Since printf() cannot be used in kernel threads (it uses too much stack space) don't export it for modules either. This should leave us exporting only things that are absolutely critical (such as memset and friends) and things that are injected by the compiler (stack guard and similar.) Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: hostfs: define our own API boundary

2023-04-20T21:04:40Z

Instead of exporting the set of functions provided by glibc that are needed for hostfs_user.c, just build that into the kernel image whenever hostfs is built, and then export _those_ functions cleanly, to be independent of the libc implementation. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger

um: add __weak for exported functions

2023-04-20T20:57:00Z

If the exported glibc functions don't exist, we get link failures. Avoid that by adding __weak so they're allowed to not exist. Reported-by: Randy Dunlap Signed-off-by: Johannes Berg Acked-by: Randy Dunlap Tested-by: Randy Dunlap Signed-off-by: Richard Weinberger

ELF: fix all "Elf" typos

2023-04-08T20:45:37Z

ELF is acronym and therefore should be spelled in all caps. I left one exception at Documentation/arm/nwfpe/nwfpe.rst which looks like being written in the first person. Link: https://lkml.kernel.org/r/Y/3wGWQviIOkyLJW@p183 Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton

Merge tag 'uml-for-linus-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

2023-03-01T17:13:00Z

Pull UML updates from Richard Weinberger: - Add support for rust (yay!) - Add support for LTO - Add platform bus support to virtio-pci - Various virtio fixes - Coding style, spelling cleanups * tag 'uml-for-linus-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (27 commits) Documentation: rust: Fix arch support table uml: vector: Remove unused definitions VECTOR_{WRITE,HEADERS} um: virt-pci: properly remove PCI device from bus um: virtio_uml: move device breaking into workqueue um: virtio_uml: mark device as unregistered when breaking it um: virtio_uml: free command if adding to virtqueue failed UML: define RUNTIME_DISCARD_EXIT virt-pci: add platform bus support um-virt-pci: Make max delay configurable um: virt-pci: implement pcibios_get_phb_of_node() um: Support LTO um: put power options in a menu um: Use CFLAGS_vmlinux um: Prevent building modules incompatible with MODVERSIONS um: Avoid pcap multiple definition errors um: Make the definition of cpu_data more compatible x86: um: vdso: Add '%rcx' and '%r11' to the syscall clobber list rust: arch/um: Add support for CONFIG_RUST under x86_64 UML rust: arch/um: Disable FP/SIMD instruction to match x86 rust: arch/um: Use 'pie' relocation mode under UML ...