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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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b5cbacd7f8
Fix PROCMAP_QUERY to fetch optional build ID only after dropping mmap_lock or per-VMA lock, whichever was used to lock VMA under question, to avoid deadlock reported by syzbot: -> #1 (&mm->mmap_lock){++++}-{4:4}: __might_fault+0xed/0x170 _copy_to_iter+0x118/0x1720 copy_page_to_iter+0x12d/0x1e0 filemap_read+0x720/0x10a0 blkdev_read_iter+0x2b5/0x4e0 vfs_read+0x7f4/0xae0 ksys_read+0x12a/0x250 do_syscall_64+0xcb/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&sb->s_type->i_mutex_key#8){++++}-{4:4}: __lock_acquire+0x1509/0x26d0 lock_acquire+0x185/0x340 down_read+0x98/0x490 blkdev_read_iter+0x2a7/0x4e0 __kernel_read+0x39a/0xa90 freader_fetch+0x1d5/0xa80 __build_id_parse.isra.0+0xea/0x6a0 do_procmap_query+0xd75/0x1050 procfs_procmap_ioctl+0x7a/0xb0 __x64_sys_ioctl+0x18e/0x210 do_syscall_64+0xcb/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&mm->mmap_lock); lock(&sb->s_type->i_mutex_key#8); lock(&mm->mmap_lock); rlock(&sb->s_type->i_mutex_key#8); *** DEADLOCK *** This seems to be exacerbated (as we haven't seen these syzbot reports before that) by the recent:777a8560fd("lib/buildid: use __kernel_read() for sleepable context") To make this safe, we need to grab file refcount while VMA is still locked, but other than that everything is pretty straightforward. Internal build_id_parse() API assumes VMA is passed, but it only needs the underlying file reference, so just add another variant build_id_parse_file() that expects file passed directly. [akpm@linux-foundation.org: fix up kerneldoc] Link: https://lkml.kernel.org/r/20260129215340.3742283-1-andrii@kernel.org Fixes:ed5d583a88("fs/procfs: implement efficient VMA querying API for /proc/<pid>/maps") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Reported-by: <syzbot+4e70c8e0a2017b432f7a@syzkaller.appspotmail.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Tested-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Eduard Zingerman <eddyz87@gmail.com> Cc: Hao Luo <haoluo@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: Song Liu <song@kernel.org> Cc: Stanislav Fomichev <sdf@fomichev.me> Cc: Yonghong Song <yonghong.song@linux.dev> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
50 lines
1.3 KiB
C
50 lines
1.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_BUILDID_H
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#define _LINUX_BUILDID_H
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#include <linux/types.h>
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#define BUILD_ID_SIZE_MAX 20
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struct vm_area_struct;
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struct file;
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int build_id_parse(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size);
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int build_id_parse_file(struct file *file, unsigned char *build_id, __u32 *size);
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int build_id_parse_nofault(struct vm_area_struct *vma, unsigned char *build_id, __u32 *size);
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int build_id_parse_buf(const void *buf, unsigned char *build_id, u32 buf_size);
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#if IS_ENABLED(CONFIG_STACKTRACE_BUILD_ID) || IS_ENABLED(CONFIG_VMCORE_INFO)
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extern unsigned char vmlinux_build_id[BUILD_ID_SIZE_MAX];
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void init_vmlinux_build_id(void);
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#else
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static inline void init_vmlinux_build_id(void) { }
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#endif
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struct freader {
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void *buf;
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u32 buf_sz;
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int err;
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union {
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struct {
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struct file *file;
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struct folio *folio;
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void *addr;
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loff_t folio_off;
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bool may_fault;
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};
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struct {
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const char *data;
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u64 data_sz;
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};
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};
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};
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void freader_init_from_file(struct freader *r, void *buf, u32 buf_sz,
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struct file *file, bool may_fault);
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void freader_init_from_mem(struct freader *r, const char *data, u64 data_sz);
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const void *freader_fetch(struct freader *r, loff_t file_off, size_t sz);
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void freader_cleanup(struct freader *r);
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#endif
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