The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 156e42996bd84eccb6acf319f19ce0cb140d00e3 Mon Sep 17 00:00:00 2001
From: Mike Salvatore mike.salvatore@canonical.com Date: Wed, 12 Jun 2019 14:55:14 -0700 Subject: [PATCH] apparmor: reset pos on failure to unpack for various functions
Each function that manipulates the aa_ext struct should reset it's "pos" member on failure. This ensures that, on failure, no changes are made to the state of the aa_ext struct.
There are paths were elements are optional and the error path is used to indicate the optional element is not present. This means instead of just aborting on error the unpack stream can become unsynchronized on optional elements, if using one of the affected functions.
Cc: stable@vger.kernel.org Fixes: 736ec752d95e ("AppArmor: policy routines for loading and unpacking policy") Signed-off-by: Mike Salvatore mike.salvatore@canonical.com Signed-off-by: John Johansen john.johansen@canonical.com
diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c index 005a705346f0..8cfc9493eefc 100644 --- a/security/apparmor/policy_unpack.c +++ b/security/apparmor/policy_unpack.c @@ -219,16 +219,21 @@ static void *kvmemdup(const void *src, size_t len) static size_t unpack_u16_chunk(struct aa_ext *e, char **chunk) { size_t size = 0; + void *pos = e->pos;
if (!inbounds(e, sizeof(u16))) - return 0; + goto fail; size = le16_to_cpu(get_unaligned((__le16 *) e->pos)); e->pos += sizeof(__le16); if (!inbounds(e, size)) - return 0; + goto fail; *chunk = e->pos; e->pos += size; return size; + +fail: + e->pos = pos; + return 0; }
/* unpack control byte */ @@ -290,62 +295,84 @@ static bool unpack_nameX(struct aa_ext *e, enum aa_code code, const char *name)
static bool unpack_u8(struct aa_ext *e, u8 *data, const char *name) { + void *pos = e->pos; + if (unpack_nameX(e, AA_U8, name)) { if (!inbounds(e, sizeof(u8))) - return 0; + goto fail; if (data) *data = get_unaligned((u8 *)e->pos); e->pos += sizeof(u8); return 1; } + +fail: + e->pos = pos; return 0; }
static bool unpack_u32(struct aa_ext *e, u32 *data, const char *name) { + void *pos = e->pos; + if (unpack_nameX(e, AA_U32, name)) { if (!inbounds(e, sizeof(u32))) - return 0; + goto fail; if (data) *data = le32_to_cpu(get_unaligned((__le32 *) e->pos)); e->pos += sizeof(u32); return 1; } + +fail: + e->pos = pos; return 0; }
static bool unpack_u64(struct aa_ext *e, u64 *data, const char *name) { + void *pos = e->pos; + if (unpack_nameX(e, AA_U64, name)) { if (!inbounds(e, sizeof(u64))) - return 0; + goto fail; if (data) *data = le64_to_cpu(get_unaligned((__le64 *) e->pos)); e->pos += sizeof(u64); return 1; } + +fail: + e->pos = pos; return 0; }
static size_t unpack_array(struct aa_ext *e, const char *name) { + void *pos = e->pos; + if (unpack_nameX(e, AA_ARRAY, name)) { int size; if (!inbounds(e, sizeof(u16))) - return 0; + goto fail; size = (int)le16_to_cpu(get_unaligned((__le16 *) e->pos)); e->pos += sizeof(u16); return size; } + +fail: + e->pos = pos; return 0; }
static size_t unpack_blob(struct aa_ext *e, char **blob, const char *name) { + void *pos = e->pos; + if (unpack_nameX(e, AA_BLOB, name)) { u32 size; if (!inbounds(e, sizeof(u32))) - return 0; + goto fail; size = le32_to_cpu(get_unaligned((__le32 *) e->pos)); e->pos += sizeof(u32); if (inbounds(e, (size_t) size)) { @@ -354,6 +381,9 @@ static size_t unpack_blob(struct aa_ext *e, char **blob, const char *name) return size; } } + +fail: + e->pos = pos; return 0; }
@@ -370,9 +400,10 @@ static int unpack_str(struct aa_ext *e, const char **string, const char *name) if (src_str[size - 1] != 0) goto fail; *string = src_str; + + return size; } } - return size;
fail: e->pos = pos;