The patch titled Subject: c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal has been added to the -mm tree. Its filename is c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> Subject: c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal [ fix for "c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-v2" from mm tree ] After removing mm->num_exe_file_vmas kernel keeps mm->exe_file until final mmput(), it never becomes NULL while task is alive. We can check for other mapped files in mm instead of checking mm->num_exe_file_vmas, and mark mm with flag MMF_EXE_FILE_CHANGED in order to forbid second changing of mm->exe_file. Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> Reviewed-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Matt Helsley <matthltc@xxxxxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/sched.h | 1 + kernel/sys.c | 31 +++++++++++++++++++------------ 2 files changed, 20 insertions(+), 12 deletions(-) diff -puN include/linux/sched.h~c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal include/linux/sched.h --- a/include/linux/sched.h~c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal +++ a/include/linux/sched.h @@ -437,6 +437,7 @@ extern int get_dumpable(struct mm_struct /* leave room for more dump flags */ #define MMF_VM_MERGEABLE 16 /* KSM may merge identical pages */ #define MMF_VM_HUGEPAGE 17 /* set when VM_HUGEPAGE is set on vma */ +#define MMF_EXE_FILE_CHANGED 18 /* see prctl_set_mm_exe_file() */ #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK) diff -puN kernel/sys.c~c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal kernel/sys.c --- a/kernel/sys.c~c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal +++ a/kernel/sys.c @@ -1714,17 +1714,11 @@ static bool vma_flags_mismatch(struct vm static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd) { + struct vm_area_struct *vma; struct file *exe_file; struct dentry *dentry; int err; - /* - * Setting new mm::exe_file is only allowed when no VM_EXECUTABLE vma's - * remain. So perform a quick test first. - */ - if (mm->num_exe_file_vmas) - return -EBUSY; - exe_file = fget(fd); if (!exe_file) return -EBADF; @@ -1745,17 +1739,30 @@ static int prctl_set_mm_exe_file(struct if (err) goto exit; + down_write(&mm->mmap_sem); + + /* + * Forbid mm->exe_file change if there are mapped other files. + */ + err = -EBUSY; + for (vma = mm->mmap; vma; vma = vma->vm_next) { + if (vma->vm_file && !path_equal(&vma->vm_file->f_path, + &exe_file->f_path)) + goto exit_unlock; + } + /* * The symlink can be changed only once, just to disallow arbitrary * transitions malicious software might bring in. This means one * could make a snapshot over all processes running and monitor * /proc/pid/exe changes to notice unusual activity if needed. */ - down_write(&mm->mmap_sem); - if (likely(!mm->exe_file)) - set_mm_exe_file(mm, exe_file); - else - err = -EBUSY; + err = -EPERM; + if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags)) + goto exit_unlock; + + set_mm_exe_file(mm, exe_file); +exit_unlock: up_write(&mm->mmap_sem); exit: _ Subject: Subject: c/r: prctl: update prctl_set_mm_exe_file() after mm->num_exe_file_vmas removal Patches currently in -mm which might be from khlebnikov@xxxxxxxxxx are mm-hugetlb-fix-warning-in-alloc_huge_page-dequeue_huge_page_vma.patch linux-next.patch mm-correctly-synchronize-rss-counters-at-exit-exec.patch mm-correctly-synchronize-rss-counters-at-exit-exec-fix.patch mm-correctly-synchronize-rss-counters-at-exit-exec-set-task-exit-code-before-complete_vfork_done.patch mm-remove-swap-token-code.patch mm-vmscan-remove-lumpy-reclaim.patch mm-vmscan-do-not-stall-on-writeback-during-memory-compaction.patch mm-vmscan-remove-reclaim_mode_t.patch mm-memcg-scanning_global_lru-means-mem_cgroup_disabled.patch mm-memcg-move-reclaim_stat-into-lruvec.patch mm-push-lru-index-into-shrink_active_list.patch mm-push-lru-index-into-shrink_active_list-fix.patch mm-mark-mm-inline-functions-as-__always_inline.patch mm-remove-lru-type-checks-from-__isolate_lru_page.patch mm-memcg-kill-mem_cgroup_lru_del.patch mm-memcg-use-vm_swappiness-from-target-memory-cgroup.patch fork-call-complete_vfork_done-after-clearing-child_tid-and-flushing-rss-counters.patch c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html