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| author | Jiri Kosina <jkosina@suse.cz> | 2016-07-08 11:38:28 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-07-08 11:52:58 +0200 |
| commit | 39380b80d72723282f0ea1d1bbf2294eae45013e (patch) | |
| tree | 988c97a00f253be7f86a53931d314ce5c08a920f /drivers/char/mem.c | |
| parent | Merge tag 'v4.7-rc6' into x86/mm, to merge fixes before applying new changes (diff) | |
| download | linux-39380b80d72723282f0ea1d1bbf2294eae45013e.tar.xz linux-39380b80d72723282f0ea1d1bbf2294eae45013e.zip | |
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.c | 6 |
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++; } |