kernel/linux.git/fs/binfmt_elf.c, branch v5.15.208

fs/binfmt_elf: Fix memory leak in load_elf_binary()

2022-11-03T14:59:12+00:00

commit 594d2a14f2168c09b13b114c3d457aa939403e52 upstream. There is a memory leak reported by kmemleak: unreferenced object 0xffff88817104ef80 (size 224): comm "xfs_admin", pid 47165, jiffies 4298708825 (age 1333.476s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 60 a8 b3 00 81 88 ff ff a8 10 5a 00 81 88 ff ff `.........Z..... backtrace: [] __alloc_file+0x21/0x250 [] alloc_empty_file+0x41/0xf0 [] path_openat+0xea/0x3d30 [] do_filp_open+0x1b9/0x290 [] do_open_execat+0xce/0x5b0 [] open_exec+0x27/0x50 [] load_elf_binary+0x510/0x3ed0 [] bprm_execve+0x599/0x1240 [] do_execveat_common.isra.0+0x4c7/0x680 [] __x64_sys_execve+0x88/0xb0 [] do_syscall_64+0x35/0x80 If "interp_elf_ex" fails to allocate memory in load_elf_binary(), the program will take the "out_free_ph" error handing path, resulting in "interpreter" file resource is not released. Fix it by adding an error handing path "out_free_file", which will release the file resource when "interp_elf_ex" failed to allocate memory. Fixes: 0693ffebcfe5 ("fs/binfmt_elf.c: allocate less for static executable") Signed-off-by: Li Zetao Reviewed-by: Alexey Dobriyan Signed-off-by: Kees Cook Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20221024154421.982230-1-lizetao1@huawei.com Signed-off-by: Greg Kroah-Hartman

coredump: Use the vma snapshot in fill_files_note

2022-04-08T12:24:18+00:00

commit 390031c942116d4733310f0684beb8db19885fe6 upstream. Matthew Wilcox reported that there is a missing mmap_lock in file_files_note that could possibly lead to a user after free. Solve this by using the existing vma snapshot for consistency and to avoid the need to take the mmap_lock anywhere in the coredump code except for dump_vma_snapshot. Update the dump_vma_snapshot to capture vm_pgoff and vm_file that are neeeded by fill_files_note. Add free_vma_snapshot to free the captured values of vm_file. Reported-by: Matthew Wilcox Link: https://lkml.kernel.org/r/20220131153740.2396974-1-willy@infradead.org Cc: stable@vger.kernel.org Fixes: a07279c9a8cd ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot") Fixes: 2aa362c49c31 ("coredump: extend core dump note section to contain file names of mapped files") Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman

coredump/elf: Pass coredump_params into fill_note_info

2022-04-08T12:24:17+00:00

commit 9ec7d3230717b4fe9b6c7afeb4811909c23fa1d7 upstream. Instead of individually passing cprm->siginfo and cprm->regs into fill_note_info pass all of struct coredump_params. This is preparation to allow fill_files_note to use the existing vma snapshot. Reviewed-by: Jann Horn Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman

coredump: Snapshot the vmas in do_coredump

2022-04-08T12:24:17+00:00

commit 95c5436a4883841588dae86fb0b9325f47ba5ad3 upstream. Move the call of dump_vma_snapshot and kvfree(vma_meta) out of the individual coredump routines into do_coredump itself. This makes the code less error prone and easier to maintain. Make the vma snapshot available to the coredump routines in struct coredump_params. This makes it easier to change and update what is captures in the vma snapshot and will be needed for fixing fill_file_notes. Reviewed-by: Jann Horn Reviewed-by: Kees Cook Signed-off-by: "Eric W. Biederman" Signed-off-by: Greg Kroah-Hartman

fs/binfmt_elf: Fix AT_PHDR for unusual ELF files

2022-04-08T12:23:56+00:00

[ Upstream commit 0da1d5002745cdc721bc018b582a8a9704d56c42 ] BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=197921 As pointed out in the discussion of buglink, we cannot calculate AT_PHDR as the sum of load_addr and exec->e_phoff. : The AT_PHDR of ELF auxiliary vectors should point to the memory address : of program header. But binfmt_elf.c calculates this address as follows: : : NEW_AUX_ENT(AT_PHDR, load_addr + exec->e_phoff); : : which is wrong since e_phoff is the file offset of program header and : load_addr is the memory base address from PT_LOAD entry. : : The ld.so uses AT_PHDR as the memory address of program header. In normal : case, since the e_phoff is usually 64 and in the first PT_LOAD region, it : is the correct program header address. : : But if the address of program header isn't equal to the first PT_LOAD : address + e_phoff (e.g. Put the program header in other non-consecutive : PT_LOAD region), ld.so will try to read program header from wrong address : then crash or use incorrect program header. This is because exec->e_phoff is the offset of PHDRs in the file and the address of PHDRs in the memory may differ from it. This patch fixes the bug by calculating the address of program headers from PT_LOADs directly. Signed-off-by: Akira Kawata Reported-by: kernel test robot Acked-by: Kees Cook Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220127124014.338760-2-akirakawata1@gmail.com Signed-off-by: Sasha Levin

elf: don't use MAP_FIXED_NOREPLACE for elf interpreter mappings

2021-10-03T21:02:58+00:00

In commit b212921b13bd ("elf: don't use MAP_FIXED_NOREPLACE for elf executable mappings") we still leave MAP_FIXED_NOREPLACE in place for load_elf_interp. Unfortunately, this will cause kernel to fail to start with: 1 (init): Uhuuh, elf segment at 00003ffff7ffd000 requested but the memory is mapped already Failed to execute /init (error -17) The reason is that the elf interpreter (ld.so) has overlapping segments. readelf -l ld-2.31.so Program Headers: Type Offset VirtAddr PhysAddr FileSiz MemSiz Flags Align LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000 0x000000000002c94c 0x000000000002c94c R E 0x10000 LOAD 0x000000000002dae0 0x000000000003dae0 0x000000000003dae0 0x00000000000021e8 0x0000000000002320 RW 0x10000 LOAD 0x000000000002fe00 0x000000000003fe00 0x000000000003fe00 0x00000000000011ac 0x0000000000001328 RW 0x10000 The reason for this problem is the same as described in commit ad55eac74f20 ("elf: enforce MAP_FIXED on overlaying elf segments"). Not only executable binaries, elf interpreters (e.g. ld.so) can have overlapping elf segments, so we better drop MAP_FIXED_NOREPLACE and go back to MAP_FIXED in load_elf_interp. Fixes: 4ed28639519c ("fs, elf: drop MAP_FIXED usage from elf_map") Cc: # v4.19 Cc: Andrew Morton Cc: Michal Hocko Signed-off-by: Chen Jingwen Signed-off-by: Linus Torvalds

binfmt: remove in-tree usage of MAP_DENYWRITE

2021-09-03T16:42:01+00:00

At exec time when we mmap the new executable via MAP_DENYWRITE we have it opened via do_open_execat() and already deny_write_access()'ed the file successfully. Once exec completes, we allow_write_acces(); however, we set mm->exe_file in begin_new_exec() via set_mm_exe_file() and also deny_write_access() as long as mm->exe_file remains set. We'll effectively deny write access to our executable via mm->exe_file until mm->exe_file is changed -- when the process is removed, on new exec, or via sys_prctl(PR_SET_MM_MAP/EXE_FILE). Let's remove all usage of MAP_DENYWRITE, it's no longer necessary for mm->exe_file. In case of an elf interpreter, we'll now only deny write access to the file during exec. This is somewhat okay, because the interpreter behaves (and sometime is) a shared library; all shared libraries, especially the ones loaded directly in user space like via dlopen() won't ever be mapped via MAP_DENYWRITE, because we ignore that from user space completely; these shared libraries can always be modified while mapped and executed. Let's only special-case the main executable, denying write access while being executed by a process. This can be considered a minor user space visible change. While this is a cleanup, it also fixes part of a problem reported with VM_DENYWRITE on overlayfs, as VM_DENYWRITE is effectively unused with this patch and will be removed next: "Overlayfs did not honor positive i_writecount on realfile for VM_DENYWRITE mappings." [1] [1] https://lore.kernel.org/r/YNHXzBgzRrZu1MrD@miu.piliscsaba.redhat.com/ Reported-by: Chengguang Xu Acked-by: "Eric W. Biederman" Acked-by: Christian König Signed-off-by: David Hildenbrand

binfmt: don't use MAP_DENYWRITE when loading shared libraries via uselib()

2021-09-03T16:42:01+00:00

uselib() is the legacy systemcall for loading shared libraries. Nowadays, applications use dlopen() to load shared libraries, completely implemented in user space via mmap(). For example, glibc uses MAP_COPY to mmap shared libraries. While this maps to MAP_PRIVATE | MAP_DENYWRITE on Linux, Linux ignores any MAP_DENYWRITE specification from user space in mmap. With this change, all remaining in-tree users of MAP_DENYWRITE use it to map an executable. We will be able to open shared libraries loaded via uselib() writable, just as we already can via dlopen() from user space. This is one step into the direction of removing MAP_DENYWRITE from the kernel. This can be considered a minor user space visible change. Acked-by: "Eric W. Biederman" Acked-by: Christian König Signed-off-by: David Hildenbrand

Merge branch 'akpm' (patches from Andrew)

2021-06-30T00:29:11+00:00

Merge misc updates from Andrew Morton: "191 patches. Subsystems affected by this patch series: kthread, ia64, scripts, ntfs, squashfs, ocfs2, kernel/watchdog, and mm (gup, pagealloc, slab, slub, kmemleak, dax, debug, pagecache, gup, swap, memcg, pagemap, mprotect, bootmem, dma, tracing, vmalloc, kasan, initialization, pagealloc, and memory-failure)" * emailed patches from Andrew Morton : (191 commits) mm,hwpoison: make get_hwpoison_page() call get_any_page() mm,hwpoison: send SIGBUS with error virutal address mm/page_alloc: split pcp->high across all online CPUs for cpuless nodes mm/page_alloc: allow high-order pages to be stored on the per-cpu lists mm: replace CONFIG_FLAT_NODE_MEM_MAP with CONFIG_FLATMEM mm: replace CONFIG_NEED_MULTIPLE_NODES with CONFIG_NUMA docs: remove description of DISCONTIGMEM arch, mm: remove stale mentions of DISCONIGMEM mm: remove CONFIG_DISCONTIGMEM m68k: remove support for DISCONTIGMEM arc: remove support for DISCONTIGMEM arc: update comment about HIGHMEM implementation alpha: remove DISCONTIGMEM and NUMA mm/page_alloc: move free_the_page mm/page_alloc: fix counting of managed_pages mm/page_alloc: improve memmap_pages dbg msg mm: drop SECTION_SHIFT in code comments mm/page_alloc: introduce vm.percpu_pagelist_high_fraction mm/page_alloc: limit the number of pages on PCP lists when reclaim is active mm/page_alloc: scale the number of pages that are batch freed ...

binfmt: remove in-tree usage of MAP_EXECUTABLE

2021-06-29T17:53:50+00:00

Ever since commit e9714acf8c43 ("mm: kill vma flag VM_EXECUTABLE and mm->num_exe_file_vmas"), VM_EXECUTABLE is gone and MAP_EXECUTABLE is essentially completely ignored. Let's remove all usage of MAP_EXECUTABLE. [akpm@linux-foundation.org: fix blooper in fs/binfmt_aout.c. per David] Link: https://lkml.kernel.org/r/20210421093453.6904-3-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: "Eric W. Biederman" Reviewed-by: Kees Cook Cc: Alexander Shishkin Cc: Alexander Viro Cc: Arnaldo Carvalho de Melo Cc: Borislav Petkov Cc: Catalin Marinas Cc: Don Zickus Cc: Feng Tang Cc: Greg Ungerer Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jiri Olsa Cc: Kevin Brodsky Cc: Mark Rutland Cc: Michal Hocko Cc: Mike Rapoport Cc: Namhyung Kim Cc: Peter Zijlstra Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds