The backport of commit 7c03e2cda4a5 ("vfs: move cap_convert_nscap() call
into vfs_setxattr()") did not consider that vfs_setxattr had other exit
paths that would require a converted value to be freed.
If xattr_permission returns a failure, it would cause a memory leak. In the
case of security.capability attribute, which is the only that can allocate
a new value, xattr_permission will return a failure in case of
HAS_UNMAPPED_ID(inode), which would already be caught by cap_convert_nscap,
at !capable_wrt_inode_uidgid(inode, CAP_SETFCAP).
However, if the file IS_IMMUTABLE or IS_APPEND, the failure will be
returned and the leak will happen.
Though setting a file as immutable or append is restricted to
CAP_FILE_IMMUTABLE, the leak was still shown to happen when trying to
setcap on an immutable file after doing a mount unshare.
Signed-off-by: Thadeu Lima de Souza Cascardo <email address hidden>
Acked-by: Krzysztof Kozlowski <email address hidden>
Acked-by: Andy Whitcroft <email address hidden>
Signed-off-by: Stefan Bader <email address hidden>
UBUNTU: SAUCE: bpf, x86: Validate computation of branch displacements for x86-64
The branch displacement logic in the BPF JIT compilers for x86 assumes
that, for any generated branch instruction, the distance cannot
increase between optimization passes.
But this assumption can be violated due to how the distances are
computed. Specifically, whenever a backward branch is processed in
do_jit(), the distance is computed by subtracting the positions in the
machine code from different optimization passes. This is because part
of addrs[] is already updated for the current optimization pass, before
the branch instruction is visited.
And so the optimizer can expand blocks of machine code in some cases.
This can confuse the optimizer logic, where it assumes that a fixed
point has been reached for all machine code blocks once the total
program size stops changing. And then the JIT compiler can output
abnormal machine code containing incorrect branch displacements.
To mitigate this issue, we assert that a fixed point is reached while
populating the output image. This rejects any problematic programs.
The issue affects both x86-32 and x86-64. We mitigate separately to
ease backporting.
Signed-off-by: Piotr Krysiuk <email address hidden>
Reviewed-by: Daniel Borkmann <email address hidden>
Signed-off-by: Daniel Borkmann <email address hidden>
(backported from commit e4d4d456436bfb2fe412ee2cd489f7658449b098)
git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git)
[cascardo: conflict on message, kept new one, so users can find more
references about it]
CVE-2021-29154
Signed-off-by: Thadeu Lima de Souza Cascardo <email address hidden>
Acked-by: Guilherme G. Piccoli <email address hidden>
Acked-by: Colin King <email address hidden>
