Memory-safety fixes: uninitialized reads and a realloc leak - #613
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Four sites used a value that may never have been set: - tape_get_pews leaves *pews unset on -LTFS_UNSUPPORTED, which the caller treats as non-fatal before computing pews + 10. - ltfs_profiler_set left ret unset when the volume had neither an iosched nor a device handle, then tested it. - _get_dump derived a transfer length from cap_buf without checking the READ BUFFER result, so a failed read produced a garbage length. - the ICU normalize helpers leave their output pointer unset on error, but the callers compared that pointer against the input (to decide whether to free a no-op result) before checking the return code, reading uninitialized memory and potentially leaking the input buffer. Initialize pews and ret, check the READ BUFFER result, and check the normalize return code before the pointer comparison in all five callers.
realloc was assigned back to priv.dk_list, so a failure overwrote the only pointer to the existing buffer with NULL and leaked it. Use a temporary and free the original on failure.
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Thanks for all your work, just some correctness comments :DD
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| if (priv.dk_list) { | ||
| unsigned char *expanded = (unsigned char*)realloc(priv.dk_list, dk_list_len); | ||
| if (expanded == NULL) { | ||
| ltfsmsg(LTFS_ERR, 10001E, __FUNCTION__); | ||
| free(priv.dk_list); | ||
| return -LTFS_NO_MEMORY; | ||
| } | ||
| priv.dk_list = expanded; | ||
| } else { | ||
| priv.dk_list = (unsigned char*)calloc(dk_list_len, sizeof(unsigned char)); | ||
| if (priv.dk_list == NULL) { | ||
| ltfsmsg(LTFS_ERR, 10001E, __FUNCTION__); | ||
| return -LTFS_NO_MEMORY; | ||
| if (priv.dk_list == NULL) { | ||
| ltfsmsg(LTFS_ERR, 10001E, __FUNCTION__); | ||
| return -LTFS_NO_MEMORY; | ||
| } |
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This change seems to add more unnecessary complexity and repeated code. Maybe adding the brackets for clarity can be a good change. The added free on the original error path should be enough.
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| /* ret stays unset if neither the iosched nor device handle is present; | ||
| * the final "if (!ret && ret_save)" would then read garbage. */ |
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This comment is out of scope for documentation, there's no need to over explain the initialization of the variable. Was this AI generated?
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| /* icu_nfd is unset on error; free the input and bail before | ||
| * comparing the (garbage) output pointer. */ |
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| /* *new_name is unset on error; free the input and bail before | ||
| * comparing the (garbage) output pointer. */ |
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| /* tape_get_pews leaves this unset when it returns -LTFS_UNSUPPORTED, | ||
| * which the caller treats as non-fatal and then reads pews; default to 0 | ||
| * so the fallback (pews + 10) is deterministic. */ |
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| /* cap_buf is indeterminate on failure; do not derive a transfer | ||
| * length from it. */ |
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Two commits:
tape_get_pewsleaves*pewsunset on-LTFS_UNSUPPORTEDwhile the caller computespews + 10;ltfs_profiler_settested an unsetretwhen the volume had neither an iosched nor a device handle;_get_dumpderived a transfer length fromcap_bufwithout checking the READ BUFFER result; the ICU normalize callers compared the output pointer against the input before checking the return code, reading uninitialized memory and potentially leaking the input buffer.reallocwas assigned straight back topriv.dk_list, so a failure overwrote the only pointer to the existing buffer with NULL and leaked it.