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From: buildroot@browserseal.com (Sasha Sirotkin)
To: linux-arm-kernel@lists.infradead.org
Subject: kernel virtual memory access (from app) does not generate segfault
Date: Tue, 20 Apr 2010 12:14:30 +0300	[thread overview]
Message-ID: <4BCD7076.9030802@browserseal.com> (raw)

More specifically, writing from usermode application to a kernel virtual 
memory address on ARM does  result in segmentation fault, however 
calling a function in this memory region for some reason does not.

For instance, this code generates a segfault allright

int * aa;
aa = 0xc0000000;
*aa=42;

However this code does not, instead the process simply hangs (and can be 
killed)

void (*func)(void);
func = 0xc0000000;
func();

I stumbled across this by accident. Just curious to understand why it 
happens. Isn't it a bug ?


P.S. My kernel is 2.6.32.7 and the CPU is ARM926EJ-S rev 5 (v5l)

             reply	other threads:[~2010-04-20  9:14 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-20  9:14 Sasha Sirotkin [this message]
2010-04-20  9:34 ` kernel virtual memory access (from app) does not generate segfault Ben Dooks
2010-04-20 10:27   ` Dave P. Martin
2010-04-20 14:20     ` anfei
2010-04-20 17:09       ` Ben Dooks
2010-04-20 19:28         ` Russell King - ARM Linux
2010-04-20 22:31           ` Jamie Lokier
2010-04-20 22:41             ` Russell King - ARM Linux
2010-04-21  0:33               ` Jamie Lokier
2010-04-21 11:17               ` kernel virtual memory access (from app) does not generatesegfault Dave P. Martin
2010-04-21 12:43                 ` anfei
2010-04-21 16:07                   ` Dave P. Martin
2010-04-21 19:16                     ` Jamie Lokier
2010-04-21 19:40                       ` Russell King - ARM Linux
2010-04-21 21:00                         ` Jamie Lokier
2010-04-21 19:36                   ` Russell King - ARM Linux
2010-04-21 19:35                 ` Russell King - ARM Linux
2010-04-21 21:24                   ` Nicolas Pitre
2010-04-21 21:44                     ` Russell King - ARM Linux
2010-04-21 21:54                       ` Russell King - ARM Linux
2010-04-21 22:59                         ` Nicolas Pitre
2010-04-22 10:56                           ` Dave P. Martin
2010-04-22 12:29                             ` anfei
2010-04-22 13:18                               ` Dave P. Martin
2010-04-22 15:59                                 ` Jamie Lokier
2010-04-21 13:11           ` kernel virtual memory access (from app) does not generate segfault anfei
2010-04-21 19:45             ` Jamie Lokier
2010-06-08 13:29             ` anfei
2010-06-08 13:36               ` Russell King - ARM Linux
2010-06-08 14:19                 ` anfei

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