Messages in this thread Patch in this message | | | Date | Mon, 12 Sep 2005 23:13:21 +0200 | From | Michal Piotrowski <> | Subject | Re: 2.6.13-mm3 [OOPS] vfs, page_owner, full reproductively, badness in vsnprintf |
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Hi,
On 12/09/05, Alexander Nyberg <alexn@telia.com> wrote: > > Gah, I'm such a fantastic programmer. > > I don't know what mc is up to but the error checking in read_page_owner > is flawed wrt snprintf which could cause the 'size' argument to snprintf > to become negative and if so overwrite beyond 'buf'. > > Again, I fail to see how mc causes this to happen, but this fixes it > by proper error checking. > > Signed-off-by: Alexander Nyberg <alexn@telia.com>
Thanks, patch solved problem. Here is version, that clean apply on 2.6.13-mm3. Can you review it?
Regards, Michal Piotrowski
Signed-off-by: Michal K. K. Piotrowski <michal.k.k.piotrowski@gmail.com>
diff -uprN -X linux-mm-clean/Documentation/dontdiff linux-mm-clean/fs/proc/proc_misc.c linux-mm/fs/proc/proc_misc.c --- linux-mm-clean/fs/proc/proc_misc.c 2005-09-12 23:02:10.000000000 +0200 +++ linux-mm/fs/proc/proc_misc.c 2005-09-12 22:52:51.000000000 +0200 @@ -567,6 +567,7 @@ read_page_owner(struct file *file, char char namebuf[128]; unsigned long offset = 0, symsize; int i; + ssize_t num_written = 0; pfn = min_low_pfn + *ppos; page = pfn_to_page(pfn); @@ -587,23 +588,41 @@ read_page_owner(struct file *file, char kbuf = kmalloc(count, GFP_KERNEL); if (!kbuf) return -ENOMEM; + ret = snprintf(kbuf, count, "Page allocated via order %d, mask 0x%x\n", page->order, page->gfp_mask); + if (ret >= count) { + ret = -ENOMEM; + goto out; + } + + num_written = ret; - ret = snprintf(kbuf, 1024, "Page allocated via order %d, mask 0x%x\n", - page->order, page->gfp_mask); for (i = 0; i < 8; i++) { if (!page->trace[i]) break; symname = kallsyms_lookup(page->trace[i], &symsize, &offset, &modname, namebuf); - ret += snprintf(kbuf + ret, count - ret, "[0x%lx] %s+%lu\n", + ret = snprintf(kbuf + num_written, count - num_written, "[0x%lx] %s+%lu\n", page->trace[i], namebuf, offset); + if (ret >= count - num_written) { + ret = -ENOMEM; + goto out; + } + num_written += ret; + } + ret = snprintf(kbuf + num_written, count - num_written, "\n"); + if (ret >= count - num_written) { + ret = -ENOMEM; + goto out; + } - ret += snprintf(kbuf + ret, count -ret, "\n"); + num_written += ret; + ret = num_written; if (copy_to_user(buf, kbuf, ret)) ret = -EFAULT; +out: kfree(kbuf); return ret; } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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