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fs: ntfs3: Fix possible null-pointer dereferences in mi_read()

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In a previous commit 2681631c29 ("fs/ntfs3: Add null pointer check to
attr_load_runs_vcn"), ni can be NULL in attr_load_runs_vcn(), and thus it
should be checked before being used.

However, in the call stack of this commit, mft_ni in mi_read() is
aliased with ni in attr_load_runs_vcn(), and it is also used in
mi_read() at two places:

mi_read()
  rw_lock = &mft_ni->file.run_lock -> No check
  attr_load_runs_vcn(mft_ni, ...)
    ni (namely mft_ni) is checked in the previous commit
  attr_load_runs_vcn(..., &mft_ni->file.run) -> No check

Thus, to avoid possible null-pointer dereferences, the related checks
should be added.

These bugs are reported by a static analysis tool implemented by myself,
and they are found by extending a known bug fixed in the previous commit.
Thus, they could be theoretical bugs.

Signed-off-by: Jia-Ju Bai <baijiaju@buaa.edu.cn>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
This commit is contained in:
Jia-Ju Bai 2023-03-21 21:22:11 +08:00 committed by Konstantin Komarov
parent c9db0ff046
commit 97498cd610
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GPG Key ID: A9B0331F832407B6
1 changed files with 2 additions and 2 deletions
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4
fs/ntfs3/record.c
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@ -124,7 +124,7 @@ int mi_read(struct mft_inode *mi, bool is_mft)
struct rw_semaphore *rw_lock = NULL;
if (is_mounted(sbi)) {
if (!is_mft) {
if (!is_mft && mft_ni) {
rw_lock = &mft_ni->file.run_lock;
down_read(rw_lock);
}
@ -148,7 +148,7 @@ int mi_read(struct mft_inode *mi, bool is_mft)
ni_lock(mft_ni);
down_write(rw_lock);
}
err = attr_load_runs_vcn(mft_ni, ATTR_DATA, NULL, 0, &mft_ni->file.run,
err = attr_load_runs_vcn(mft_ni, ATTR_DATA, NULL, 0, run,
vbo >> sbi->cluster_bits);
if (rw_lock) {
up_write(rw_lock);