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a3bf0f28d4statmount_mnt_idmap() writes one mapping with seq_printf() and then
manually advances seq->count to include the NUL separator.
If seq_printf() overflows, seq_set_overflow() sets seq->count to
seq->size. The manual seq->count++ changes this to seq->size + 1.
seq_has_overflowed() then no longer detects the overflow. The corrupted
count returns to statmount_string(), which later executes:
seq->buf[seq->count++] = '\0';
This causes a 1-byte NULL out-of-bounds write on the dynamically
allocated seq buffer.
Fix this by checking for overflow immediately after seq_printf().
Fixes: 37c4a9590e ("statmount: allow to retrieve idmappings")
Signed-off-by: Junyoung Jang <graypanda.inzag@gmail.com>
Link: https://patch.msgid.link/20260504112649.1862936-1-graypanda.inzag@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
389 lines
10 KiB
389 lines
10 KiB