From 118901ad1f25d2334255b3d50512fa20591531cd Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 4 Jan 2023 13:09:12 -0800 Subject: ext4: Fix function prototype mismatch for ext4_feat_ktype With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. ext4_feat_ktype was setting the "release" handler to "kfree", which doesn't have a matching function prototype. Add a simple wrapper with the correct prototype. This was found as a result of Clang's new -Wcast-function-type-strict flag, which is more sensitive than the simpler -Wcast-function-type, which only checks for type width mismatches. Note that this code is only reached when ext4 is a loadable module and it is being unloaded: CFI failure at kobject_put+0xbb/0x1b0 (target: kfree+0x0/0x180; expected type: 0x7c4aa698) ... RIP: 0010:kobject_put+0xbb/0x1b0 ... Call Trace: ext4_exit_sysfs+0x14/0x60 [ext4] cleanup_module+0x67/0xedb [ext4] Fixes: b99fee58a20a ("ext4: create ext4_feat kobject dynamically") Cc: Theodore Ts'o Cc: Eric Biggers Cc: stable@vger.kernel.org Build-tested-by: Gustavo A. R. Silva Reviewed-by: Gustavo A. R. Silva Reviewed-by: Nathan Chancellor Link: https://lore.kernel.org/r/20230103234616.never.915-kees@kernel.org Signed-off-by: Kees Cook Reviewed-by: Eric Biggers Link: https://lore.kernel.org/r/20230104210908.gonna.388-kees@kernel.org --- fs/ext4/sysfs.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c index d233c24ea342..e2b8b3437c58 100644 --- a/fs/ext4/sysfs.c +++ b/fs/ext4/sysfs.c @@ -491,6 +491,11 @@ static void ext4_sb_release(struct kobject *kobj) complete(&sbi->s_kobj_unregister); } +static void ext4_feat_release(struct kobject *kobj) +{ + kfree(kobj); +} + static const struct sysfs_ops ext4_attr_ops = { .show = ext4_attr_show, .store = ext4_attr_store, @@ -505,7 +510,7 @@ static struct kobj_type ext4_sb_ktype = { static struct kobj_type ext4_feat_ktype = { .default_groups = ext4_feat_groups, .sysfs_ops = &ext4_attr_ops, - .release = (void (*)(struct kobject *))kfree, + .release = ext4_feat_release, }; void ext4_notify_error_sysfs(struct ext4_sb_info *sbi) -- cgit v1.2.3 From 48df133578c70185a95a49390d42df1996ddba2a Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 27 Jan 2023 14:39:21 -0800 Subject: coda: Avoid partial allocation of sig_inputArgs GCC does not like having a partially allocated object, since it cannot reason about it for bounds checking when it is passed to other code. Instead, fully allocate sig_inputArgs. (Alternatively, sig_inputArgs should be defined as a struct coda_in_hdr, if it is actually not using any other part of the union.) Seen under GCC 13: ../fs/coda/upcall.c: In function 'coda_upcall': ../fs/coda/upcall.c:801:22: warning: array subscript 'union inputArgs[0]' is partly outside array bounds of 'unsigned char[20]' [-Warray-bounds=] 801 | sig_inputArgs->ih.opcode = CODA_SIGNAL; | ^~ Cc: Jan Harkes Cc: coda@cs.cmu.edu Cc: codalist@coda.cs.cmu.edu Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20230127223921.never.882-kees@kernel.org --- fs/coda/upcall.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/coda/upcall.c b/fs/coda/upcall.c index 59f6cfd06f96..cd6a3721f6f6 100644 --- a/fs/coda/upcall.c +++ b/fs/coda/upcall.c @@ -791,7 +791,7 @@ static int coda_upcall(struct venus_comm *vcp, sig_req = kmalloc(sizeof(struct upc_req), GFP_KERNEL); if (!sig_req) goto exit; - sig_inputArgs = kvzalloc(sizeof(struct coda_in_hdr), GFP_KERNEL); + sig_inputArgs = kvzalloc(sizeof(*sig_inputArgs), GFP_KERNEL); if (!sig_inputArgs) { kfree(sig_req); goto exit; -- cgit v1.2.3