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DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1729253727; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=/I1t6dr9YxkUDtjU+LCeHcvfcO9HKB+cT/uD7iPasWs=; b=RfO4TxRWnCCgRwEmMh7HRw0CCQGyRoYUzgbBa1mmGxG1YQ8kPU1i4wtlmeI16T14PNzhbU 4TG3OjcAQtNR/pJLNq386tgKmQHe99ruEI3ri3tDSeWw3rdyvZBk7UIv5JTw+QEYsYi1kV ern8WXnnhwWuQ+/DQ6IHmDe6NWqC3Y4= From: Thorsten Blum To: Alexander Viro , Christian Brauner , Jan Kara , Kees Cook , "Gustavo A. R. Silva" , Thorsten Blum Cc: Nathan Chancellor , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2] acl: Annotate struct posix_acl with __counted_by() Date: Fri, 18 Oct 2024 14:14:21 +0200 Message-ID: <20241018121426.155247-2-thorsten.blum@linux.dev> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Add the __counted_by compiler attribute to the flexible array member a_entries to improve access bounds-checking via CONFIG_UBSAN_BOUNDS and CONFIG_FORTIFY_SOURCE. Use struct_size() to calculate the number of bytes to allocate for new and cloned acls and remove the local size variables. Change the posix_acl_alloc() function parameter count from int to unsigned int to match posix_acl's a_count data type. Add identifier names to the function definition to silence two checkpatch warnings. Reviewed-by: Jan Kara Signed-off-by: Thorsten Blum Cc: Nathan Chancellor --- Changes in v2: - Update patch to apply cleanly to linux-next. With 8f0a7a2d7bc3 ("acl: Realign struct posix_acl to save 8 bytes") in -next, this patch should not trigger the false-positive buffer overflow anymore - Link to v1: https://lore.kernel.org/linux-kernel/20240923213809.235128-2-thorsten.blum@linux.dev/ --- fs/posix_acl.c | 13 ++++++------- include/linux/posix_acl.h | 4 ++-- 2 files changed, 8 insertions(+), 9 deletions(-) diff --git a/fs/posix_acl.c b/fs/posix_acl.c index 6c66a37522d0..4050942ab52f 100644 --- a/fs/posix_acl.c +++ b/fs/posix_acl.c @@ -200,11 +200,11 @@ EXPORT_SYMBOL(posix_acl_init); * Allocate a new ACL with the specified number of entries. */ struct posix_acl * -posix_acl_alloc(int count, gfp_t flags) +posix_acl_alloc(unsigned int count, gfp_t flags) { - const size_t size = sizeof(struct posix_acl) + - count * sizeof(struct posix_acl_entry); - struct posix_acl *acl = kmalloc(size, flags); + struct posix_acl *acl; + + acl = kmalloc(struct_size(acl, a_entries, count), flags); if (acl) posix_acl_init(acl, count); return acl; @@ -220,9 +220,8 @@ posix_acl_clone(const struct posix_acl *acl, gfp_t flags) struct posix_acl *clone = NULL; if (acl) { - int size = sizeof(struct posix_acl) + acl->a_count * - sizeof(struct posix_acl_entry); - clone = kmemdup(acl, size, flags); + clone = kmemdup(acl, struct_size(acl, a_entries, acl->a_count), + flags); if (clone) refcount_set(&clone->a_refcount, 1); } diff --git a/include/linux/posix_acl.h b/include/linux/posix_acl.h index 2d6a4badd306..e2d47eb1a7f3 100644 --- a/include/linux/posix_acl.h +++ b/include/linux/posix_acl.h @@ -30,7 +30,7 @@ struct posix_acl { refcount_t a_refcount; unsigned int a_count; struct rcu_head a_rcu; - struct posix_acl_entry a_entries[]; + struct posix_acl_entry a_entries[] __counted_by(a_count); }; #define FOREACH_ACL_ENTRY(pa, acl, pe) \ @@ -62,7 +62,7 @@ posix_acl_release(struct posix_acl *acl) /* posix_acl.c */ extern void posix_acl_init(struct posix_acl *, int); -extern struct posix_acl *posix_acl_alloc(int, gfp_t); +extern struct posix_acl *posix_acl_alloc(unsigned int count, gfp_t flags); extern struct posix_acl *posix_acl_from_mode(umode_t, gfp_t); extern int posix_acl_equiv_mode(const struct posix_acl *, umode_t *); extern int __posix_acl_create(struct posix_acl **, gfp_t, umode_t *);