diff options
authorKees Cook <>2010-04-22 12:19:17 -0700
committerGreg Kroah-Hartman <>2010-05-26 14:29:21 -0700
commit734c542a8aa9d7d49ffed09e671972851f25df5e (patch)
parent9e79d5307f9e53930b1cca4440e2691e0c4d0293 (diff)
mmap_min_addr check CAP_SYS_RAWIO only for write
commit 4ae69e6b718589abe97c9625ccbb1e0bc95a8c0e upstream. Redirecting directly to lsm, here's the patch discussed on lkml: The mmap_min_addr value is useful information for an admin to see without being root ("is my system vulnerable to kernel NULL pointer attacks?") and its setting is trivially easy for an attacker to determine by calling mmap() in PAGE_SIZE increments starting at 0, so trying to keep it private has no value. Only require CAP_SYS_RAWIO if changing the value, not reading it. Comment from Serge : Me, I like to write my passwords with light blue pen on dark blue paper, pasted on my window - if you're going to get my password, you're gonna get a headache. Signed-off-by: Kees Cook <> Acked-by: Serge Hallyn <> Signed-off-by: James Morris <> (cherry picked from commit 822cceec7248013821d655545ea45d1c6a9d15b3) Signed-off-by: Greg Kroah-Hartman <>
1 files changed, 1 insertions, 1 deletions
diff --git a/security/min_addr.c b/security/min_addr.c
index fc43c9d37084..d9f94258c108 100644
--- a/security/min_addr.c
+++ b/security/min_addr.c
@@ -33,7 +33,7 @@ int mmap_min_addr_handler(struct ctl_table *table, int write,
int ret;
- if (!capable(CAP_SYS_RAWIO))
+ if (write && !capable(CAP_SYS_RAWIO))
return -EPERM;
ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);