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authorJiri Kosina <jkosina@suse.cz>2016-07-08 11:38:28 +0200
committerIngo Molnar <mingo@kernel.org>2016-07-08 11:52:58 +0200
commit39380b80d72723282f0ea1d1bbf2294eae45013e (patch)
tree988c97a00f253be7f86a53931d314ce5c08a920f /drivers/char/mem.c
parent946e0f6ffcaa614012d646f4cf84efdd62628c8b (diff)
downloadlinux-39380b80d72723282f0ea1d1bbf2294eae45013e.tar.bz2
x86/mm/pat, /dev/mem: Remove superfluous error message
Currently it's possible for broken (or malicious) userspace to flood a kernel log indefinitely with messages a-la Program dmidecode tried to access /dev/mem between f0000->100000 because range_is_allowed() is case of CONFIG_STRICT_DEVMEM being turned on dumps this information each and every time devmem_is_allowed() fails. Reportedly userspace that is able to trigger contignuous flow of these messages exists. It would be possible to rate limit this message, but that'd have a questionable value; the administrator wouldn't get information about all the failing accessess, so then the information would be both superfluous and incomplete at the same time :) Returning EPERM (which is what is actually happening) is enough indication for userspace what has happened; no need to log this particular error as some sort of special condition. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Kees Cook <keescook@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luis R. Rodriguez <mcgrof@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Toshi Kani <toshi.kani@hp.com> Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1607081137020.24757@cbobk.fhfr.pm Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'drivers/char/mem.c')
-rw-r--r--drivers/char/mem.c6
1 files changed, 1 insertions, 5 deletions
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 71025c2f6bbb..d633974e7f8b 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -66,12 +66,8 @@ static inline int range_is_allowed(unsigned long pfn, unsigned long size)
u64 cursor = from;
while (cursor < to) {
- if (!devmem_is_allowed(pfn)) {
- printk(KERN_INFO
- "Program %s tried to access /dev/mem between %Lx->%Lx.\n",
- current->comm, from, to);
+ if (!devmem_is_allowed(pfn))
return 0;
- }
cursor += PAGE_SIZE;
pfn++;
}