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Date: Tue, 17 Apr 2012 02:55:20 +0400 From: Cyrill Gorcunov <gorcunov@...nvz.org> To: LKML <linux-kernel@...r.kernel.org> Cc: Andrew Morton <akpm@...ux-foundation.org>, Kees Cook <keescook@...omium.org>, Tejun Heo <tj@...nel.org>, Serge Hallyn <serge.hallyn@...onical.com>, Pavel Emelyanov <xemul@...allels.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Subject: [PATCH c/r -mm] c/r: prctl: Simplify PR_SET_MM on mm::code/data assignment The mm::start_code, end_code, start_data, end_data members are set during startup of executable file and are not changed after. But the program itself might map new executable or/and data areas in time so the original values written into mm fields mentioned above might not have correspond VMA area at all, thus if one try to use this prctl codes without underlied VMA, the error will be returned. Drop this requirement. This shrinks the code and eliminates redundant calls to vma_flags_mismatch. The worst thing one can do (if say to write some bad values here) -- the weird results will be shown in /proc/$pid/statm or in /proc/pid/stat. Still, assignement of data on stack (such as command line and environment variables) requires the underlied VMA to exist. Signed-off-by: Cyrill Gorcunov <gorcunov@...nvz.org> Cc: Kees Cook <keescook@...omium.org> Cc: Tejun Heo <tj@...nel.org> Cc: Serge Hallyn <serge.hallyn@...onical.com> Cc: Pavel Emelyanov <xemul@...allels.com> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> Cc: Andrew Morton <akpm@...ux-foundation.org> --- This code is under CONFIG_CHECKPOINT_RESTORE. I would really appreciate some review, just to check I've not missed something. kernel/sys.c | 34 ++++++++-------------------------- 1 file changed, 8 insertions(+), 26 deletions(-) Index: linux-2.6.git/kernel/sys.c =================================================================== --- linux-2.6.git.orig/kernel/sys.c +++ linux-2.6.git/kernel/sys.c @@ -1777,38 +1777,18 @@ static int prctl_set_mm(int opt, unsigne down_read(&mm->mmap_sem); vma = find_vma(mm, addr); - if (opt != PR_SET_MM_START_BRK && - opt != PR_SET_MM_BRK && - opt != PR_SET_MM_AUXV) { - /* It must be existing VMA */ - if (!vma || vma->vm_start > addr) - goto out; - } - - error = -EINVAL; switch (opt) { case PR_SET_MM_START_CODE: + mm->start_code = addr; + break; case PR_SET_MM_END_CODE: - if (vma_flags_mismatch(vma, VM_READ | VM_EXEC, - VM_WRITE | VM_MAYSHARE)) - goto out; - - if (opt == PR_SET_MM_START_CODE) - mm->start_code = addr; - else - mm->end_code = addr; + mm->end_code = addr; break; - case PR_SET_MM_START_DATA: + mm->start_data = addr; + break; case PR_SET_MM_END_DATA: - if (vma_flags_mismatch(vma, VM_READ | VM_WRITE, - VM_EXEC | VM_MAYSHARE)) - goto out; - - if (opt == PR_SET_MM_START_DATA) - mm->start_data = addr; - else - mm->end_data = addr; + mm->end_data = addr; break; case PR_SET_MM_START_BRK: @@ -1847,6 +1827,8 @@ static int prctl_set_mm(int opt, unsigne case PR_SET_MM_ARG_END: case PR_SET_MM_ENV_START: case PR_SET_MM_ENV_END: + if (!vma) + goto out; #ifdef CONFIG_STACK_GROWSUP if (vma_flags_mismatch(vma, VM_READ | VM_WRITE | VM_GROWSUP, 0)) #else -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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