From 1e624196f43c3a62122959e15c5f03572cdadb5d Mon Sep 17 00:00:00 2001 From: Ram Gupta Date: Mon, 10 Apr 2006 22:52:57 -0700 Subject: [PATCH] [PATCH] mm: fix bug in brk() The code checks for newbrk with oldbrk which are page aligned before making a check for the memory limit set of data segment. If the memory limit is not page aligned in that case it bypasses the test for the limit if the memory allocation is still for the same page. Signed-off-by: Ram Gupta Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mmap.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index e780d19aa214..eab6fcb65e11 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -220,6 +220,17 @@ asmlinkage unsigned long sys_brk(unsigned long brk) if (brk < mm->end_code) goto out; + + /* + * Check against rlimit here. If this check is done later after the test + * of oldbrk with newbrk then it can escape the test and let the data + * segment grow beyond its set limit the in case where the limit is + * not page aligned -Ram Gupta + */ + rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; + if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) + goto out; + newbrk = PAGE_ALIGN(brk); oldbrk = PAGE_ALIGN(mm->brk); if (oldbrk == newbrk) @@ -232,11 +243,6 @@ asmlinkage unsigned long sys_brk(unsigned long brk) goto out; } - /* Check against rlimit.. */ - rlim = current->signal->rlim[RLIMIT_DATA].rlim_cur; - if (rlim < RLIM_INFINITY && brk - mm->start_data > rlim) - goto out; - /* Check against existing mmap mappings. */ if (find_vma_intersection(mm, oldbrk, newbrk+PAGE_SIZE)) goto out; -- GitLab