3.2-stable review patch. If anyone has any objections, please let me know.
------------------ From: Siddhesh Poyarekar <[email protected]> commit 7edc8b0ac16cbaed7cb4ea4c6b95ce98d2997e84 upstream. The vma length in dup_mmap is calculated and stored in a unsigned int, which is insufficient and hence overflows for very large maps (beyond 16TB). The following program demonstrates this: #include <stdio.h> #include <unistd.h> #include <sys/mman.h> #define GIG 1024 * 1024 * 1024L #define EXTENT 16393 int main(void) { int i, r; void *m; char buf[1024]; for (i = 0; i < EXTENT; i++) { m = mmap(NULL, (size_t) 1 * 1024 * 1024 * 1024L, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0); if (m == (void *)-1) printf("MMAP Failed: %d\n", m); else printf("%d : MMAP returned %p\n", i, m); r = fork(); if (r == 0) { printf("%d: successed\n", i); return 0; } else if (r < 0) printf("FORK Failed: %d\n", r); else if (r > 0) wait(NULL); } return 0; } Increase the storage size of the result to unsigned long, which is sufficient for storing the difference between addresses. Signed-off-by: Siddhesh Poyarekar <[email protected]> Cc: Tejun Heo <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Jens Axboe <[email protected]> Cc: Peter Zijlstra <[email protected]> Acked-by: Hugh Dickins <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <[email protected]> --- kernel/fork.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/kernel/fork.c +++ b/kernel/fork.c @@ -352,7 +352,8 @@ } charge = 0; if (mpnt->vm_flags & VM_ACCOUNT) { - unsigned int len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; + unsigned long len; + len = (mpnt->vm_end - mpnt->vm_start) >> PAGE_SHIFT; if (security_vm_enough_memory(len)) goto fail_nomem; charge = len; -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
