We introduced setname ioctl in commit bb2bb90304 ("dma-buf:
add DMA_BUF_SET_NAME ioctls") that provides userpsace
to attach a free-form name for tracking and counting shared
buffers. However the d_dname callback could be called in atomic
context. This call path comes from selinux that verifies all
inherited open files from exec call. To verify all inherited
open files, kernel would iterate all fds which need to hold
spin_lock to get denty name by calling d_dname operation.
In dma-buf d_dname callback, we use mutex lock to prevent the
race from setname causing this issue.
This commit adds a spinlock to protect set/get name operation
to fix this issue.
[ 165.617090] Call trace:
[ 165.620504] ___might_sleep+0x114/0x118
[ 165.625344] __might_sleep+0x50/0x84
[ 165.629928] __mutex_lock_common+0x5c/0x10b0
[ 165.635215] mutex_lock_nested+0x40/0x50
[ 165.640157] dmabuffs_dname+0x48/0xdc
[ 165.644821] d_path+0x78/0x1e4
[ 165.648870] audit_log_d_path+0x68/0x134
[ 165.653807] common_lsm_audit+0x33c/0x6f4
[ 165.658832] slow_avc_audit+0xb4/0xf0
[ 165.663503] avc_has_perm+0xdc/0x1a4
[ 165.668081] file_has_perm+0x70/0x154
[ 165.672750] match_file+0x54/0x6c
[ 165.677064] iterate_fd+0x74/0xac
[ 165.681369] selinux_bprm_committing_creds+0xfc/0x210
[ 165.687459] security_bprm_committing_creds+0x2c/0x40
[ 165.693546] install_exec_creds+0x1c/0x68
[ 165.698569] load_elf_binary+0x3a0/0x13c8
[ 165.703590] search_binary_handler+0xb8/0x1e4
[ 165.708964] __do_execve_file+0x6e4/0x9c8
[ 165.713984] __arm64_sys_execve+0x44/0x54
[ 165.719008] el0_svc_common+0xa8/0x168
[ 165.723765] el0_svc_handler+0x78/0x94
[ 165.728522] el0_svc+0x8/0xc
Signed-off-by: Martin Liu <liumartin@google.com>
[surenb: cherry-picked and backported from:
https://lkml.org/lkml/2020/1/14/799
Conflicts:
drivers/dma-buf/dma-buf.c
1. Resolved diffs between 4.19 and upstream by replacing dma_resv_lock
with dmabuf->lock
]
Bug: 150611569
Test: build
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: Ia0b20a40d491eb41b8844d05dc86dfd6039de07f
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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