https://github.com/torvalds/linux
Revision 6348dd291e3653534a9e28e6917569bc9967b35b authored by Charan Teja Kalla on 19 June 2020, 11:57:19 UTC, committed by Sumit Semwal on 10 July 2020, 10:09:29 UTC
There exists a sleep-while-atomic bug while accessing the dmabuf->name under mutex in the dmabuffs_dname(). This is caused from the SELinux permissions checks on a process where it tries to validate the inherited files from fork() by traversing them through iterate_fd() (which traverse files under spin_lock) and call match_file(security/selinux/hooks.c) where the permission checks happen. This audit information is logged using dump_common_audit_data() where it calls d_path() to get the file path name. If the file check happen on the dmabuf's fd, then it ends up in ->dmabuffs_dname() and use mutex to access dmabuf->name. The flow will be like below: flush_unauthorized_files() iterate_fd() spin_lock() --> Start of the atomic section. match_file() file_has_perm() avc_has_perm() avc_audit() slow_avc_audit() common_lsm_audit() dump_common_audit_data() audit_log_d_path() d_path() dmabuffs_dname() mutex_lock()--> Sleep while atomic. Call trace captured (on 4.19 kernels) is below: ___might_sleep+0x204/0x208 __might_sleep+0x50/0x88 __mutex_lock_common+0x5c/0x1068 __mutex_lock_common+0x5c/0x1068 mutex_lock_nested+0x40/0x50 dmabuffs_dname+0xa0/0x170 d_path+0x84/0x290 audit_log_d_path+0x74/0x130 common_lsm_audit+0x334/0x6e8 slow_avc_audit+0xb8/0xf8 avc_has_perm+0x154/0x218 file_has_perm+0x70/0x180 match_file+0x60/0x78 iterate_fd+0x128/0x168 selinux_bprm_committing_creds+0x178/0x248 security_bprm_committing_creds+0x30/0x48 install_exec_creds+0x1c/0x68 load_elf_binary+0x3a4/0x14e0 search_binary_handler+0xb0/0x1e0 So, use spinlock to access dmabuf->name to avoid sleep-while-atomic. Cc: <stable@vger.kernel.org> [5.3+] Signed-off-by: Charan Teja Kalla <charante@codeaurora.org> Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com> Acked-by: Christian König <christian.koenig@amd.com> [sumits: added comment to spinlock_t definition to avoid warning] Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org> Link: https://patchwork.freedesktop.org/patch/msgid/a83e7f0d-4e54-9848-4b58-e1acdbe06735@codeaurora.org
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Tip revision: 6348dd291e3653534a9e28e6917569bc9967b35b authored by Charan Teja Kalla on 19 June 2020, 11:57:19 UTC
dmabuf: use spinlock to access dmabuf->name
dmabuf: use spinlock to access dmabuf->name
Tip revision: 6348dd2
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arch | ||
block | ||
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lib | ||
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net | ||
samples | ||
scripts | ||
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.cocciconfig | -rw-r--r-- | 59 bytes |
.get_maintainer.ignore | -rw-r--r-- | 71 bytes |
.gitattributes | -rw-r--r-- | 62 bytes |
.gitignore | -rw-r--r-- | 1.8 KB |
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COPYING | -rw-r--r-- | 496 bytes |
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MAINTAINERS | -rw-r--r-- | 547.5 KB |
Makefile | -rw-r--r-- | 60.6 KB |
README | -rw-r--r-- | 727 bytes |
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