kernel/linux.git/fs/binfmt_flat.c, branch v5.10.257

binfmt_flat: Fix integer overflow bug on 32 bit systems

2025-03-13T11:47:06+00:00

commit 55cf2f4b945f6a6416cc2524ba740b83cc9af25a upstream. Most of these sizes and counts are capped at 256MB so the math doesn't result in an integer overflow. The "relocs" count needs to be checked as well. Otherwise on 32bit systems the calculation of "full_data" could be wrong. full_data = data_len + relocs * sizeof(unsigned long); Fixes: c995ee28d29d ("binfmt_flat: prevent kernel dammage from corrupted executable headers") Cc: stable@vger.kernel.org Signed-off-by: Dan Carpenter Acked-by: Nicolas Pitre Link: https://lore.kernel.org/r/5be17f6c-5338-43be-91ef-650153b975cb@stanley.mountain Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

binfmt_flat: do not stop relocating GOT entries prematurely on riscv

2022-06-09T08:20:47+00:00

commit 6045ab5fea4c849153ebeb0acb532da5f29d69c4 upstream. bFLT binaries are usually created using elf2flt. The linker script used by elf2flt has defined the .data section like the following for the last 19 years: .data : { _sdata = . ; __data_start = . ; data_start = . ; *(.got.plt) *(.got) FILL(0) ; . = ALIGN(0x20) ; LONG(-1) . = ALIGN(0x20) ; ... } It places the .got.plt input section before the .got input section. The same is true for the default linker script (ld --verbose) on most architectures except x86/x86-64. The binfmt_flat loader should relocate all GOT entries until it encounters a -1 (the LONG(-1) in the linker script). The problem is that the .got.plt input section starts with a GOTPLT header (which has size 16 bytes on elf64-riscv and 8 bytes on elf32-riscv), where the first word is set to -1. See the binutils implementation for riscv [1]. This causes the binfmt_flat loader to stop relocating GOT entries prematurely and thus causes the application to crash when running. Fix this by skipping the whole GOTPLT header, since the whole GOTPLT header is reserved for the dynamic linker. The GOTPLT header will only be skipped for bFLT binaries with flag FLAT_FLAG_GOTPIC set. This flag is unconditionally set by elf2flt if the supplied ELF binary has the symbol _GLOBAL_OFFSET_TABLE_ defined. ELF binaries without a .got input section should thus remain unaffected. Tested on RISC-V Canaan Kendryte K210 and RISC-V QEMU nommu_virt_defconfig. [1] https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=bfd/elfnn-riscv.c;hb=binutils-2_38#l3275 Cc: Signed-off-by: Niklas Cassel Reviewed-by: Damien Le Moal Link: https://lore.kernel.org/r/20220414091018.896737-1-niklas.cassel@wdc.com Fixed-by: kernel test robot Link: https://lore.kernel.org/lkml/202204182333.OIUOotK8-lkp@intel.com Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman

binfmt_flat: revert "binfmt_flat: don't offset the data start"

2020-08-23T22:49:13+00:00

binfmt_flat loader uses the gap between text and data to store data segment pointers for the libraries. Even in the absence of shared libraries it stores at least one pointer to the executable's own data segment. Text and data can go back to back in the flat binary image and without offsetting data segment last few instructions in the text segment may get corrupted by the data segment pointer. Fix it by reverting commit a2357223c50a ("binfmt_flat: don't offset the data start"). Cc: stable@vger.kernel.org Fixes: a2357223c50a ("binfmt_flat: don't offset the data start") Signed-off-by: Max Filippov Signed-off-by: Greg Ungerer

Merge branch 'uaccess.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2020-06-10T23:02:54+00:00

Pull misc uaccess updates from Al Viro: "Assorted uaccess patches for this cycle - the stuff that didn't fit into thematic series" * 'uaccess.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: bpf: make bpf_check_uarg_tail_zero() use check_zeroed_user() x86: kvm_hv_set_msr(): use __put_user() instead of 32bit __clear_user() user_regset_copyout_zero(): use clear_user() TEST_ACCESS_OK _never_ had been checked anywhere x86: switch cp_stat64() to unsafe_put_user() binfmt_flat: don't use __put_user() binfmt_elf_fdpic: don't use __... uaccess primitives binfmt_elf: don't bother with __{put,copy_to}_user() pselect6() and friends: take handling the combined 6th/7th args into helper

binfmt_flat: use flush_icache_user_range

2020-06-08T18:05:58+00:00

load_flat_file works on user addresses. Signed-off-by: Christoph Hellwig Signed-off-by: Andrew Morton Acked-by: Greg Ungerer Cc: Alexander Viro Link: http://lkml.kernel.org/r/20200515143646.3857579-28-hch@lst.de Signed-off-by: Linus Torvalds

binfmt_flat: don't use __put_user()

2020-06-03T20:58:53+00:00

... and check the return value Signed-off-by: Al Viro

exec: Rename flush_old_exec begin_new_exec

2020-05-07T21:55:47+00:00

There is and has been for a very long time been a lot more going on in flush_old_exec than just flushing the old state. After the movement of code from setup_new_exec there is a whole lot more going on than just flushing the old executables state. Rename flush_old_exec to begin_new_exec to more accurately reflect what this function does. Reviewed-by: Kees Cook Reviewed-by: Greg Ungerer Signed-off-by: "Eric W. Biederman"

exec: Merge install_exec_creds into setup_new_exec

2020-05-07T21:55:47+00:00

The two functions are now always called one right after the other so merge them together to make future maintenance easier. Reviewed-by: Kees Cook Reviewed-by: Greg Ungerer Signed-off-by: "Eric W. Biederman"

binfmt: Move install_exec_creds after setup_new_exec to match binfmt_elf

2020-05-07T21:54:27+00:00

In 2016 Linus moved install_exec_creds immediately after setup_new_exec, in binfmt_elf as a cleanup and as part of closing a potential information leak. Perform the same cleanup for the other binary formats. Different binary formats doing the same things the same way makes exec easier to reason about and easier to maintain. Greg Ungerer reports: > I tested the the whole series on non-MMU m68k and non-MMU arm > (exercising binfmt_flat) and it all tested out with no problems, > so for the binfmt_flat changes: Tested-by: Greg Ungerer Ref: 9f834ec18def ("binfmt_elf: switch to new creds when switching to new mm") Reviewed-by: Kees Cook Reviewed-by: Greg Ungerer Signed-off-by: "Eric W. Biederman"

fs/binfmt_flat.c: remove set but not used variable 'inode'

2019-07-17T02:23:22+00:00

Fixes gcc '-Wunused-but-set-variable' warning: fs/binfmt_flat.c: In function load_flat_file: fs/binfmt_flat.c:419:16: warning: variable inode set but not used [-Wunused-but-set-variable] It's never used and can be removed. Link: http://lkml.kernel.org/r/20190525125341.9844-1-yuehaibing@huawei.com Signed-off-by: YueHaibing Cc: Al Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds