Re: [PATCH] vsprintf: drop comment claiming %n is ignored

[Joe Perches]

On Wed, 2013-09-11 at 13:18 -0700, Kees Cook wrote:
> On Wed, Sep 11, 2013 at 1:06 PM, Joe Perches <joe@xxxxxxxxxxx> wrote:
> > On Wed, 2013-09-11 at 12:30 -0700, Kees Cook wrote:
> >> The %n format is not ignored, so remove the incorrect comment about it.
> >
> > I think it may be better to reimplement the ignoring.
> 
> Yeah, just had a quick look, and scanf doesn't use this code at all.
> I'd much rather remove %n again instead.
> 
> > Maybe:
> > ---
> >  lib/vsprintf.c      | 18 +++++-------
> >  net/ipv4/fib_trie.c | 30 +++++++++----------
> >  net/ipv4/ping.c     | 19 ++++++------
> >  net/ipv4/tcp_ipv4.c | 84 ++++++++++++++++++++++++++---------------------------
> >  net/ipv4/udp.c      | 19 ++++++------
> >  net/phonet/socket.c | 32 ++++++++++----------
> >  net/sctp/objcnt.c   |  5 ++--
> >  7 files changed, 99 insertions(+), 108 deletions(-)
> 
> This needs fs/proc/consoles.c, nommu.c, task_mmu.c, and task_nommu.c
> added too, if I can believe my "git grep".

Yeah, just found those too.
---
 fs/proc/consoles.c   |  2 +-
 fs/proc/nommu.c      | 20 ++++++++++----------
 fs/proc/task_mmu.c   | 18 +++++++++---------
 fs/proc/task_nommu.c | 20 ++++++++++----------
 4 files changed, 30 insertions(+), 30 deletions(-)

diff --git a/fs/proc/consoles.c b/fs/proc/consoles.c
index b701eaa..42f2bb7 100644
--- a/fs/proc/consoles.c
+++ b/fs/proc/consoles.c
@@ -47,7 +47,7 @@ static int show_console_dev(struct seq_file *m, void *v)
 			con_flags[a].name : ' ';
 	flags[a] = 0;
 
-	seq_printf(m, "%s%d%n", con->name, con->index, &len);
+	len = seq_printf(m, "%s%d", con->name, con->index);
 	len = 21 - len;
 	if (len < 1)
 		len = 1;
diff --git a/fs/proc/nommu.c b/fs/proc/nommu.c
index ccfd99b..91cfd19 100644
--- a/fs/proc/nommu.c
+++ b/fs/proc/nommu.c
@@ -50,16 +50,16 @@ static int nommu_region_show(struct seq_file *m, struct vm_region *region)
 		ino = inode->i_ino;
 	}
 
-	seq_printf(m,
-		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
-		   region->vm_start,
-		   region->vm_end,
-		   flags & VM_READ ? 'r' : '-',
-		   flags & VM_WRITE ? 'w' : '-',
-		   flags & VM_EXEC ? 'x' : '-',
-		   flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
-		   ((loff_t)region->vm_pgoff) << PAGE_SHIFT,
-		   MAJOR(dev), MINOR(dev), ino, &len);
+	len = seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+			 region->vm_start,
+			 region->vm_end,
+			 flags & VM_READ ? 'r' : '-',
+			 flags & VM_WRITE ? 'w' : '-',
+			 flags & VM_EXEC ? 'x' : '-',
+			 flags & VM_MAYSHARE ?
+			 flags & VM_SHARED ? 'S' : 's' : 'p',
+			 ((loff_t)region->vm_pgoff) << PAGE_SHIFT,
+			 MAJOR(dev), MINOR(dev), ino);
 
 	if (file) {
 		len = 25 + sizeof(void *) * 6 - len;
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 107d026..f84ee9f 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -286,15 +286,15 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 	if (stack_guard_page_end(vma, end))
 		end -= PAGE_SIZE;
 
-	seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
-			start,
-			end,
-			flags & VM_READ ? 'r' : '-',
-			flags & VM_WRITE ? 'w' : '-',
-			flags & VM_EXEC ? 'x' : '-',
-			flags & VM_MAYSHARE ? 's' : 'p',
-			pgoff,
-			MAJOR(dev), MINOR(dev), ino, &len);
+	len = seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+			 start,
+			 end,
+			 flags & VM_READ ? 'r' : '-',
+			 flags & VM_WRITE ? 'w' : '-',
+			 flags & VM_EXEC ? 'x' : '-',
+			 flags & VM_MAYSHARE ? 's' : 'p',
+			 pgoff,
+			 MAJOR(dev), MINOR(dev), ino);
 
 	/*
 	 * Print the dentry name for named mappings, and a
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 56123a6..1d7bbe5 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -155,16 +155,16 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
 		pgoff = (loff_t)vma->vm_pgoff << PAGE_SHIFT;
 	}
 
-	seq_printf(m,
-		   "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu %n",
-		   vma->vm_start,
-		   vma->vm_end,
-		   flags & VM_READ ? 'r' : '-',
-		   flags & VM_WRITE ? 'w' : '-',
-		   flags & VM_EXEC ? 'x' : '-',
-		   flags & VM_MAYSHARE ? flags & VM_SHARED ? 'S' : 's' : 'p',
-		   pgoff,
-		   MAJOR(dev), MINOR(dev), ino, &len);
+	len = seq_printf(m, "%08lx-%08lx %c%c%c%c %08llx %02x:%02x %lu ",
+			 vma->vm_start,
+			 vma->vm_end,
+			 flags & VM_READ ? 'r' : '-',
+			 flags & VM_WRITE ? 'w' : '-',
+			 flags & VM_EXEC ? 'x' : '-',
+			 flags & VM_MAYSHARE ?
+			 flags & VM_SHARED ? 'S' : 's' : 'p',
+			 pgoff,
+			 MAJOR(dev), MINOR(dev), ino);
 
 	if (file) {
 		pad_len_spaces(m, len);


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