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`struct dirent' returned from readdir(3) could be shorter (or longer) than `sizeof(struct dirent)', thus memcpy of sizeof length will overread into unallocated page causing SIGSEGV. Example stack trace: #0 0x00005555559ebeed v9fs_co_readdir_many (/usr/bin/qemu-system-x86_64 + 0x497eed) #1 0x00005555559ec2e9 v9fs_readdir (/usr/bin/qemu-system-x86_64 + 0x4982e9) #2 0x0000555555eb7983 coroutine_trampoline (/usr/bin/qemu-system-x86_64 + 0x963983) #3 0x00007ffff73e0be0 n/a (n/a + 0x0) While fixing this, provide a helper for any future `struct dirent' cloning. Resolves: https://gitlab.com/qemu-project/qemu/-/issues/841 Cc: qemu-stable@nongnu.org Co-authored-by: Christian Schoenebeck <qemu_oss@crudebyte.com> Reviewed-by: Dmitry V. Levin <ldv@altlinux.org> Signed-off-by: Vitaly Chikunov <vt@altlinux.org> Tested-by: Christian Schoenebeck <qemu_oss@crudebyte.com> Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com> Acked-by: Greg Kurz <groug@kaod.org> Tested-by: Vitaly Chikunov <vt@altlinux.org> Message-Id: <20220216181821.3481527-1-vt@altlinux.org> [C.S. - Fix typo in source comment. ] Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
76 lines
2.2 KiB
C
76 lines
2.2 KiB
C
/*
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* 9p
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*
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* Copyright IBM, Corp. 2011
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*
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* Authors:
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* Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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*
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* This work is licensed under the terms of the GNU GPL, version 2. See
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* the COPYING file in the top-level directory.
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*
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*/
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#ifndef QEMU_9P_SYNTH_H
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#define QEMU_9P_SYNTH_H
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typedef struct V9fsSynthNode V9fsSynthNode;
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typedef ssize_t (*v9fs_synth_read)(void *buf, int len, off_t offset,
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void *arg);
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typedef ssize_t (*v9fs_synth_write)(void *buf, int len, off_t offset,
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void *arg);
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typedef struct V9fsSynthNodeAttr {
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int mode;
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int inode;
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int nlink;
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v9fs_synth_read read;
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v9fs_synth_write write;
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} V9fsSynthNodeAttr;
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struct V9fsSynthNode {
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QLIST_HEAD(, V9fsSynthNode) child;
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QLIST_ENTRY(V9fsSynthNode) sibling;
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char name[NAME_MAX];
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V9fsSynthNodeAttr *attr;
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V9fsSynthNodeAttr actual_attr;
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void *private;
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int open_count;
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};
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typedef struct V9fsSynthOpenState {
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off_t offset;
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V9fsSynthNode *node;
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struct dirent dent;
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/*
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* Ensure there is enough space for 'dent' above, some systems have a
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* d_name size of just 1, which would cause a buffer overrun.
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*/
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char dent_trailing_space[NAME_MAX];
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} V9fsSynthOpenState;
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int qemu_v9fs_synth_mkdir(V9fsSynthNode *parent, int mode,
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const char *name, V9fsSynthNode **result);
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int qemu_v9fs_synth_add_file(V9fsSynthNode *parent, int mode,
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const char *name, v9fs_synth_read read,
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v9fs_synth_write write, void *arg);
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/* qtest stuff */
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#define QTEST_V9FS_SYNTH_WALK_FILE "WALK%d"
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#define QTEST_V9FS_SYNTH_LOPEN_FILE "LOPEN"
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#define QTEST_V9FS_SYNTH_WRITE_FILE "WRITE"
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/* for READDIR test */
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#define QTEST_V9FS_SYNTH_READDIR_DIR "ReadDirDir"
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#define QTEST_V9FS_SYNTH_READDIR_FILE "ReadDirFile%d"
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#define QTEST_V9FS_SYNTH_READDIR_NFILES 100
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/* Any write to the "FLUSH" file is handled one byte at a time by the
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* backend. If the byte is zero, the backend returns success (ie, 1),
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* otherwise it forces the server to try again forever. Thus allowing
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* the client to cancel the request.
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*/
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#define QTEST_V9FS_SYNTH_FLUSH_FILE "FLUSH"
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#endif
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