linux-kernel - [PATCH] Fix OOPS in show

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Date:	Fri, 10 Aug 2007 14:13:43 +0400
From:	Pavel Emelyanov <xemul@...nvz.org>
To:	Greg KH <gregkh@...e.de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
CC:	Andrew Morton <akpm@...l.org>, devel@...nvz.org
Subject: [PATCH] Fix OOPS in show_uevent()

The platform_uevent() callback called via
  show_uevent()
  dev_uevent()
  platform_uevent()
forgot to set NULL to the last envp pointer and this caused the
show_uevent() oops while printing all the envp pointers like this:

BUG: unable to handle kernel paging request at virtual address 000280d0
...
Call Trace:
 [<c04d3d2d>] vsnprintf+0x2c7/0x48c
 [<c04d3f6d>] sprintf+0x17/0x19
 [<c052efa2>] show_uevent+0xeb/0x110
 [<c0457649>] buffered_rmqueue+0x1bf/0x1ed
 [<c04577b7>] get_page_from_freelist+0x82/0xa2
 [<c0457836>] __alloc_pages+0x5f/0x286
 [<c052eeb7>] show_uevent+0x0/0x110
 [<c052ec32>] dev_attr_show+0x15/0x1c
 [<c04aa7c3>] fill_read_buffer+0x57/0x89
 [<c04aa81d>] sysfs_read_file+0x28/0x53
 [<c0471762>] vfs_read+0x7f/0xef
 [<c04719f7>] sys_read+0x3c/0x62
 [<c0404bd6>] sysenter_past_esp+0x5f/0x99
...

The last hunk in this patch fixes this.

The other problem is that the envp passed to bus, type and platform callbacks
from dev_uevent() is the same, so the callbacks can overwrite the info, written
by the others. Did I miss something important?

This is for 2.6.23-rc2-mm1

Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>

---

--- ./drivers/base/core.c.ubug	2007-08-10 14:07:26.000000000 +0400
+++ ./drivers/base/core.c	2007-08-10 14:07:15.000000000 +0400
@@ -222,6 +222,11 @@ static int dev_uevent(struct kset *kset,
 		if (retval)
 			pr_debug ("%s: bus uevent() returned %d\n",
 				  __FUNCTION__, retval);
+
+		while (*envp != NULL) {
+			envp++;
+			num_envp--;
+		}
 	}
 
 	if (dev->class && dev->class->dev_uevent) {
@@ -230,6 +235,11 @@ static int dev_uevent(struct kset *kset,
 		if (retval)
 			pr_debug("%s: class uevent() returned %d\n",
 				 __FUNCTION__, retval);
+
+		while (*envp != NULL) {
+			envp++;
+			num_envp--;
+		}
 	}
 
 	if (dev->type && dev->type->uevent) {
@@ -238,6 +248,11 @@ static int dev_uevent(struct kset *kset,
 		if (retval)
 			pr_debug("%s: dev_type uevent() returned %d\n",
 				 __FUNCTION__, retval);
+
+		while (*envp != NULL) {
+			envp++;
+			num_envp--;
+		}
 	}
 
 	return retval;
--- ./drivers/base/platform.c.ubug	2007-08-10 14:07:44.000000000 +0400
+++ ./drivers/base/platform.c	2007-08-10 13:58:55.000000000 +0400
@@ -547,6 +547,7 @@ static int platform_uevent(struct device
 
 	envp[0] = buffer;
 	snprintf(buffer, buffer_size, "MODALIAS=%s", pdev->name);
+	envp[1] = NULL;
 	return 0;
 }
 

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